Document And Entity Information
Note To Financial Statement Details Textual
Note 3 - Investment Securities
Note 4 - Loans and Allowance for Credit Losses
Income tax expense
Applicable income taxes
Note 5 - Land, Premises and Equipment, Net
Note 6 - Goodwill and Other Intangible Assets
Note 7 - Loan Servicing
Investment Tax Credit Carryforward [Member]
Note 8 - Leases
Note 9 - Deposits
Note 10 - Short-term Borrowings
Investment in Debt and Equity Securities and Other Trading Assets [Text Block]
Note 11 - Long-term Debt
Note 12 - Commitments and Contingencies
Note 13 - Share-based Compensation
Note 14 - Income Taxes
Schedule of Servicing Assets at Fair Value [Table Text Block]
Note 15 - Tax Credit Investments
Note 16 - Segment Reporting
Note 17 - Earnings Per Share
Note 18 - Derivative Instruments
Note 19 - Regulatory Matters
Note 20 - Other Comprehensive Income (Loss)
Note 22 - Fair Value of Assets and Liabilities
Note 3 - Investment Securities - Schedule of Marketable Securities (Details)
Note 3 - Investment Securities - Schedule of Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value (Details)
Note 3 - Investment Securities - Schedule of Investments Classified by Contractual Maturity Date (Details)
Note 3 - Investment Securities - Schedule of Investments (Details)
Note 4 - Loans and Allowance for Credit Losses - Schedule of Total Loans Outstanding by Portfolio Segment (Details)
Note 4 - Loans and Allowance for Credit Losses - Allowance for Loan Losses by Portfolio Segment (Details)
Note 4 - Loans and Allowance for Credit Losses - Schedule of Financing Receivable Credit Quality Indicators (Details)
Note 4 - Loans and Allowance for Credit Losses - Schedule of Loans Past Due (Details)
Note 4 - Loans and Allowance for Credit Losses - Schedule of Nonaccrual Loans by Class (Details)
Note 4 - Loans and Allowance for Credit Losses - Summary of Collateral Types (Details)
Note 5 - Land, Premises and Equipment, Net - Schedule of Property, Plant, and Equipment (Details)
Note 6 - Goodwill and Other Intangible Assets - Schedule of Goodwill (Details)
Note 6 - Goodwill and Other Intangible Assets - Schedule of Finite-Lived Intangible Assets (Details)
Note 7 - Loan Servicing - Schedule of Servicing Assets at Fair Value (Details)
Note 7 - Loan Servicing - Summary of Activity Related to Loan Servicing (Details)
Note 8 - Leases - Schedule of Lessee Assets and Liabilities (Details)
Note 8 - Leases - Schedule of Lease Cost (Details)
Note 8 - Leases - Schedule of Lessee, Operating Lease, Liability, to be Paid, Maturity (Details)
Note 9 - Deposits - Schedule of Deposit Liabilities, Type (Details)
Note 10 - Short-Term Borrowings - Schedule of Short-term Debt (Details)
Note 11 - Long-term Debt - Schedule of Long-term Debt (Details)
Note 11 - Long-term Debt - Schedule of Long-term Debt (Details) (Parentheticals)
Note 12 - Commitments and Contingencies - Schedule of Fair Value, Off Balance Sheet Risks (Details)
Note 13 - Share-based Compensation - Schedule of Share-Based Compensation for Restricted Stock and Restricted Stock Units (Details)
Note 14 - Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)
Note 15 - Tax Credit Investments - Schedule of Tax Credit Investments (Details)
Note 15 - Tax Credit Investments - Schedule of Amortization Expense and Tax Benefit (Details)
Note 16 - Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details)
Note 17 - Earnings Per Share - Schedule of Earnings Per Share, Basic and Diluted (Details)
Note 18 - Derivative Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details)
Note 18 - Derivative Instruments - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Details)
Note 18 - Derivative Instruments - Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location (Details)
Note 18 - Derivative Instruments - Schedule of Gain/(Losses) in Derivative Instruments (Details)
Note 18 - Derivative Instruments - Schedule Of Offsetting Derivative Assets And Liabilities (Details)
Note 19 - Regulatory Matters - Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations (Details)
Note 20 - Other Comprehensive Income (Loss) - Schedule of Comprehensive Income (Loss) (Details)
Land [Member]
Note 20 - Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details)
Note 22 - Fair Value of Assets and Liabilities - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details)
Note 22 - Fair Value of Assets and Liabilities - Schedule of Fair Value Assets Measured on a Nonrecurring Basis (Details)
Note 22 - Fair Value of Assets and Liabilities - Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Valuation Techniques (Details)
Note 22 - Fair Value of Assets and Liabilities - Schedule of Fair Values by Balance Sheet Groupings (Details)
Variable lease cost
Represents the amount of variable lease cost.
Notes To Financial Statements
Notes To Financial Statements [Abstract]
Leasehold Improvements [Member]
us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet
Accrued interest receivable
Segment Reporting [Text Block]
Segment Reporting [Table Text Block]
Preferred stock, $1 par value, 2,000,000 shares authorized: 0 issued and outstanding
us-gaap_Liabilities
Total liabilities
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]
us-gaap_LiabilitiesAndStockholdersEquity
Total liabilities and stockholders’ equity
us-gaap_PaymentsToAcquireTradingSecuritiesHeldforinvestment
Purchases of trading investment securities
Pledged Status [Domain]
Proceeds from sales of trading investment securities
Segment Reporting [Table]
Pledged Status [Axis]
Lessee, Lease, Description [Table]
Net increase (decrease) in short-term borrowings with maturities of three months or less
Net change in:
us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect
Net change in cash and cash equivalents
Occupancy and equipment expense
us-gaap_ServicingAssetAtFairValueAdditions
Additions from loans sold with servicing rights retained
Servicing Asset at Fair Value, Amount
Servicing rights (1)
Balance at beginning of period
Balance at end of period
Fair value of servicing rights
Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Actual
Federal Funds Purchased [Member]
Banking Regulation, Total Risk-Based Capital Ratio, Well Capitalized, Minimum
Schedule of Fair Value, off-Balance-Sheet Risks [Table Text Block]
Banking Regulation, Total Risk-Based Capital Ratio, Actual
us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations
Cash and cash equivalents at beginning of period
Cash and cash equivalents at end of period
Banking Regulation, Total Risk-Based Capital Ratio, Capital Adequacy, Minimum
Banking Regulation, Tier 1 Leverage Capital Ratio, Actual
Banking Regulation, Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum
Banking Regulation, Tier 1 Leverage Capital Ratio, Capital Adequacy, Minimum
Banking Regulation, Tier 1 Leverage Capital Ratio, Well Capitalized, Minimum
us-gaap_ServicingAssetAtFairValueChangesInFairValueResultingFromChangesInValuationInputsOrChangesInAssumptions
Change in fair value
Cash paid for amounts included in the measurement of lease liabilities operating cash flows from operating leases
us-gaap_OperatingLeasePayments
Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum
Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum
Banking Regulation, Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum
Banking Regulation, Tier 1 Risk-Based Capital Ratio, Actual
Long-Term Debt, Basis Spread on Variable Rate
Right-of-use assets obtained in exchange for new operating lease liabilities
Right-of-use assets obtained in exchange for new operating lease liabilities, net
Line of Credit Facility, Lender [Domain]
Derivative Liabilities, Fair Value
Derivatives
Financing Receivable, Allowance for Credit Loss [Table Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Outstanding, Shares (in shares)
Outstanding, Shares (in shares)
Lender Name [Axis]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Outstanding, Weighted-Average Grant Date Fair Value (in dollars per share)
Outstanding, Weighted-Average Grant Date Fair Value (in dollars per share)
Financing Receivable, Past Due [Table Text Block]
Granted, Shares (in shares)
Granted, Weighted-Average Grant Date Fair Value (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Forfeited or cancelled, Shares (in shares)
Financing Receivable Credit Quality Indicators [Table Text Block]
Banking Regulation, Mortgage Banking, Capital Requirement [Table]
Line of Credit [Member]
Vested, Weighted-Average Grant Date Fair Value (in dollars per share)
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Vested, Shares (in shares)
December 31, 2030
us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue
Total future minimum lease payments
Thereafter
Operating leases
December 31, 2027
Loans, including fees
December 31, 2026
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares)
December 31, 2029
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)
December 31, 2028
Commitments to Extend Credit [Member]
Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block]
Measurement Frequency [Axis]
Commitments and Contingencies Disclosure [Text Block]
Nature of Expense [Axis]
Fair Value Hierarchy and NAV [Axis]
Common stock, issued (in shares)
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
Common stock, outstanding (in shares)
Award Type [Domain]
Common stock, authorized (in shares)
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]
Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table]
Common stock, $1 par value, 60,000,000 and 60,000,000 shares authorized: 25,214,146 and 25,406,278 issued and outstanding
Short-Term Debt, Type [Domain]
us-gaap_PolicyTextBlockAbstract
Accounting Policies
us-gaap_DisclosureTextBlockAbstract
Notes to Financial Statements
us-gaap_TableTextBlock
Notes Tables
Comprehensive Income (Loss) Note [Text Block]
Short-Term Debt [Table]
Short-Term Debt, Type [Axis]
us-gaap_ComprehensiveIncomeNetOfTax
Total comprehensive income
Short-term borrowings
Short-Term Debt
us-gaap_FinancingReceivableUnamortizedLoanFeeCost
Financing Receivable, Unamortized Loan Cost (Fee)
us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount
Amounts representing interest
Operating lease liabilities
us-gaap_FinancingReceivableUnamortizedPurchasePremiumDiscount
Financing Receivable, Unamortized Purchase Premium (Discount)
Construction Loans [Member]
Loans Receivable [Member]
us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedGain
Unrealized Gains, Total investment securities
us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedLoss
Unrealized Losses, Total investment securities
Standby Letters of Credit [Member]
us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAllowanceForCreditLoss
Allowance for Credit Losses, Total investment securities
Long-term debt
us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityFairValue
Fair Value, Total investment securities
Statement of Stockholders' Equity [Abstract]
Statement of Comprehensive Income [Abstract]
us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAmortizedCostBeforeAllowanceForCreditLoss
Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss
Amortized Cost, Total investment securities
Statement of Cash Flows [Abstract]
Stockholders’ equity
Core Deposits [Member]
Equity Components [Axis]
Equity Component [Domain]
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member]
Equity [Text Block]
AOCI Attributable to Parent [Member]
Additional Paid-in Capital [Member]
Retained Earnings [Member]
Loans
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss
Financing Receivable, Nonaccrual [Table Text Block]
Comprehensive Income (Loss) [Table Text Block]
Amortized Cost, Held-to-maturity
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss
Total investment securities
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss
Total investment securities, Available-for-sale, Amortized Cost
Intangible Asset and Goodwill [Text Block]
alrs_IncreaseDecreaseinMortgageServicingRightsFairValue
Change in fair value of mortgage servicing rights
Represents information pertaining to the increase/decrease in the fair value of mortgage servicing rights.
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest
us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest
Allowance for credit losses on loans
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Beginning Balance
Financing Receivable, Allowance for Credit Loss, Ending Balance
Servicing rights capitalized upon sale of mortgage loans
The amount capitalized from the sale of mortgage servicing rights.
Allowance for Credit Losses, Available-for-sale
Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]
Four Years before Current Fiscal Year
Metro Phoenix Bank and HMN Financial Inc. [Member]
Represents information pertaining to Metro Phoenix Bank and HMN Financial Inc.
More than Four Years before Current Fiscal Year
Two Years before Current Fiscal Year
Three Years before Current Fiscal Year
Current Fiscal Year
Fiscal Year before Current Fiscal Year
Supplemental Cash Flow Disclosures
alrs_NumberOfBankingOffices
Number Of Banking Offices
The number of banking office.
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]
Revolving
us-gaap_LettersOfCreditOutstandingAmount
Letters of Credit Outstanding, Amount
us-gaap_ShorttermDebtFairValue
Short-term borrowings
us-gaap_LongTermDebtFairValue
Long-term debt
Tax Credit Carryforward [Table]
Lease, Cost [Table Text Block]
Tax Credit Carryforward [Axis]
Tax Credit Carryforward, Name [Domain]
Banking Regulation, Tier 1 Risk-Based Capital, Capital Adequacy, Minimum
Long-Term Debt [Text Block]
Other Commitments [Table]
Banking Regulation, Tier 1 Risk-Based Capital, Well Capitalized, Minimum
Banking Regulation, Tier 1 Risk-Based Capital, Actual
Short-Term Debt [Text Block]
Banking Regulation, Tier 1 Leverage Capital, Capital Adequacy, Minimum
Banking Regulation, Tier 1 Leverage Capital, Well Capitalized, Minimum
Banking Regulation, Tier 1 Leverage Capital, Actual
Basis of Accounting [Text Block]
Debt Instrument, Call Date
Federal Reserve
Banking Regulation, Total Risk-Based Capital, Capital Adequacy, Minimum
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]
Banking Regulation, Total Capital, Actual
Share-based compensation expense
Long-Term Debt, Carrying Value
us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
Common stock repurchased
us-gaap_NoninterestExpense
Total noninterest expense
Noninterest Expense
Long-Term Debt, Face Value
Financial Asset, Not Past Due [Member]
Banking Regulation, Total Risk-Based Capital, Well Capitalized, Minimum
Vesting of restricted stock
Debt Instrument, Name [Domain]
Debt Instrument, Maturity Date
Fair Value Measurement Inputs and Valuation Techniques [Table]
Debt Instrument, Interest Rate, Effective Percentage
Travel
Debt Instrument [Axis]
Operating Activities
Investing Activities
us-gaap_NetCashProvidedByUsedInOperatingActivities
Net cash provided (used) by operating activities
Financing Activities
us-gaap_NetCashProvidedByUsedInInvestingActivities
Net cash provided (used) by investing activities
us-gaap_NetCashProvidedByUsedInFinancingActivities
Net cash provided (used) by financing activities
Net increase (decrease) in deposits
Accounting Policies [Abstract]
US Treasury Securities [Member]
Segments [Axis]
US States and Political Subdivisions Debt Securities [Member]
us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss
Net loans
us-gaap_StockRepurchasedDuringPeriodShares
Stock Repurchased During Period, Shares (in shares)
us-gaap_PaymentsForProceedsFromLoansAndLeases
Net (increase) decrease in loans
Measurement Input Type [Axis]
Available-for-sale, at fair value (amortized cost of $528,357 and $516,737, respectively)
Debt Securities, Available-for-Sale, Excluding Accrued Interest
Total investment securities, Available-for-sale, Fair Value
Held-to-maturity, at amortized cost (fair value of $220,425 and $228,009, respectively, with an allowance for credit losses on investments of $118 and $123, respectively)
Deferred income taxes
Measurement Input, Comparability Adjustment [Member]
Measurement Input, Discount Rate [Member]
Net income
Net Income
Net income
Measurement Input, Prepayment Rate [Member]
us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
Net income available to common stockholders
Financial Asset, Past Due [Member]
us-gaap_GainLossOnSaleOfMortgageLoans
Realized loss (gain) on mortgage loans sold
Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Offset
Measurement Input Type [Domain]
us-gaap_InterestIncomeExpenseNet
Net interest income
Net interest income (loss)
Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash, Offset Against Derivative Asset
Accumulated Other Comprehensive Income (Loss) [Table]
Servicing Asset, Measurement Input
Accounting Standards Update and Change in Accounting Principle [Table]
us-gaap_OtherNoninterestExpense
Other
Amortization of operating lease right-of-use assets
In relation to the amortization of right-of-use assets.
Marketing and business development
us-gaap_NoninterestIncome
Total noninterest income
Noninterest income (loss)
Federal Home Loan Bank, Affordable Housing Program Obligation [Table Text Block]
Noninterest Income
Supplies and postage
Mortgage Interest Rate Swap [Member]
Forward based contracts in which two parties agree to swap periodic payments that are fixed at the outset of the swap contract with variable payments based on a market interest rate (index rate) over a specified period in relation to mortgages.
Measurement Basis [Axis]
us-gaap_GainsLossesOnSalesOfOtherRealEstate
Realized loss (gain) on sale of foreclosed assets
us-gaap_NoninterestIncomeOtherOperatingIncome
Other
us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestCreditLossExpenseReversal
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Credit Loss Expense (Reversal)
us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Provisions
us-gaap_DividendsCommonStock
Common stock dividends
us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Recovery
Gross charge-offs
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Charge-offs
Professional fees and assessments
us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Period Increase (Decrease)
Document Type
Due after five years through ten years, Held-to-maturity, Amortized Cost
Due after 10 years, Held-to-maturity, Amortized Cost
Document Information [Line Items]
Document Quarterly Report
Proceeds from sales or calls of investment securities available-for-sale
Amount of cash inflow from calls and sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).
Due within one year or less, Held-to-maturity, Amortized Cost
Due after one year through five years, Held-to-maturity, Amortized Cost
Operating leases (Year)
Document Information [Table]
Dilutive effect of stock-based awards (in shares)
Entity Interactive Data Current
Document Transition Report
Diluted average common shares outstanding (in shares)
Weighted-average common shares outstanding for diluted earnings per share (in shares)
Purchase accounting accretion, net
Represents the amount of accretion attributable to purchase accounting.
us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDate
Held-to-maturity, Amortized cost
Residential agency, Held-to-maturity, Amortized Cost
us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis
Available-for-sale, Amortized Cost
us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate
Available-for-sale, Fair Value
Average common shares outstanding (in shares)
us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue
Held-to-maturity, Fair Value
Derivative Instrument [Axis]
us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing
us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance
Financing Receivable, Excluding Accrued Interest, Nonaccrual, No Allowance
us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual
Financing Receivable, Excluding Accrued Interest, Nonaccrual
Interest-bearing
Total interest-bearing
us-gaap_Deposits
Total deposits
Deposits
Deposit Liabilities Disclosures [Text Block]
Noninterest-bearing
Document Fiscal Period Focus
Pledging Purpose [Axis]
Document Fiscal Year Focus
Pledging Purpose [Domain]
Investment, Name [Domain]
Customer-Related Intangible Assets [Member]
Amendment Flag
Federal Home Loan Bank Branch [Domain]
Common Stock [Member]
Federal Home Loan Bank Branch [Axis]
Document Period End Date
Commercial and Industrial Portfolio Segments [Member]
Represents information pertaining to commercial and industrial portfolio segments.
Property, Plant, and Equipment [Text Block]
Long-Lived Asset, Class [Domain]
Legal Entity [Axis]
us-gaap_InterestAndDividendIncomeOperating
Total interest income
Entity File Number
Entity Tax Identification Number
Supplemental Disclosures of Noncash Investing and Financing Activities
alrs_ReclassificationAdjustmentForNetRealizedLossesCurrentPeriodNetOfTax
Less: reclassification adjustment for net realized losses
Amount after tax of reclassification adjustments for net realized losses.
Derivative Asset, Subject to Master Netting Arrangement, before Offset
Derivative Liability, Subject to Master Netting Arrangement, before Offset
us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss
us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss
Entity [Domain]
Entity Central Index Key
Entity Registrant Name
Entity Current Reporting Status
Derivative, Gain (Loss) on Derivative, Net
us-gaap_DerivativeGainLossOnDerivativeNet
Derivative, Gain (Loss) on Derivatives, Net
Entity Incorporation, State or Country Code
Current Fiscal Year End Date
Entity Filer Category
Entity Shell Company
Entity Emerging Growth Company
Entity Small Business
Building and Building Improvements [Member]
Hedging Designation [Domain]
Derivative Asset, Fair Value
Derivatives
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
Derivative Instruments and Hedging Activities Disclosure [Text Block]
Derivative Asset, Notional Amount
Derivative Liability, Notional Amount
Entity Address, State or Province
us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale
Originations of loans held for sale
Entity Address, City or Town
Entity Address, Address Line One
Other Noninterest [Member]
Represents information pertaining to other noninterest related products and services.
City Area Code
Due after one year through five years, Available-for-sale, Amortized Cost
Due after five years through ten years, Available-for-sale, Amortized Cost
Local Phone Number
Due within one year or less, Available-for-sale, Amortized Cost
Entity Address, Postal Zip Code
Derivative [Table]
Residential agency, Available-for-sale, Fair Value
Title of 12(b) Security
Security Exchange Name
Due after five years through ten years, Available-for-sale, Fair Value
Trading Symbol
Due after 10 years, Available-for-sale, Fair Value
Due within one year or less, Available-for-sale, Fair Value
Due after one year through five years, Available-for-sale, Fair Value
Due after 10 years, Available-for-sale, Amortized Cost
Residential agency, Available-for-sale, Amortized Cost
Subsidiaries [Member]
Variable Rate [Domain]
Entity Common Stock, Shares Outstanding
Other Comprehensive Income (Loss), Net of Tax
Derivative Liability, Subject to Master Netting Arrangement, Asset Offset
Earnings Per Share [Text Block]
Hedging Designation [Axis]
Derivative Asset, Subject to Master Netting Arrangement, after Offset and Deduction
us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax
Change in fair value, tax expense (benefit)
Derivative Asset, Subject to Master Netting Arrangement, after Offset
us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax
Change in fair value, pre-tax amount
Internal Credit Assessment [Axis]
us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
Change in fair value, after-tax amount
us-gaap_BusinessCombinationAcquisitionRelatedCosts
Merger and acquisition expense
Debt Securities, Held-to-maturity, Fair Value
Total investment securities, Held-to-maturity, Fair Value
Derivative Liability, Subject to Master Netting Arrangement, after Offset and Deduction
Derivative Liability, Subject to Master Netting Arrangement, after Offset and Deduction
Derivative Liability, Subject to Master Netting Arrangement, after Offset
us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
Other comprehensive income (loss) before reclassifications
Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]
Investments Classified by Contractual Maturity Date [Table Text Block]
Internal Credit Assessment [Domain]
Due after five years through ten years, Held-to-maturity, Fair Value
Investment, Name [Axis]
Due after 10 years, Held-to-maturity, Fair Value
Due within one year or less, Held-to-maturity, Fair Value
Due after one year through five years, Held-to-maturity, Fair Value
us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
Less: Amounts reclassified from AOCI
Residential agency, Held-to-maturity, Fair Value
Receivable [Domain]
Regulatory Capital Requirements under Banking Regulations [Text Block]
us-gaap_Assets
Total assets
Total assets
Mortgage and lending expenses
The amount of mortgage and lending expenses incurred during the period.
Business services, software and technology expense
Business services, software and technology expense
The amount of business services, software and technology expenses incurred during the period.
Diluted earnings per common share (in dollars per share)
Servicing rights
Amortized amount of contract, net of valuation allowance, for servicing assets.
Proceeds from calls of investment securities held-to-maturity
The cash inflow associated with the sale or calls of securities that had been designated as held-to-maturity.
Trading
Debt Securities, Trading
Depreciation and amortization
Mortgage Receivable [Member]
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]
Disposal Group Name [Domain]
Receivable Type [Axis]
Intangible Asset, Finite-Lived [Table Text Block]
Intangible Asset, Finite-Lived [Table]
Gross charge-offs, more than five years before
Gross charge-offs, revolving
Gross charge-offs, three years before
Gross charge-offs, four years before
Gross charge-offs, prior year
Gross charge-offs, two years before
Disposal Group Name [Axis]
Gross charge-offs current year
us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration
Disposal Group, Including Discontinued Operation, Consideration
Hedging Relationship [Domain]
Forfeited or cancelled, Weighted-Average Grant Date Fair Value (in dollars per share)
us-gaap_PaymentsOfDividends
Cash dividends paid on common stock
Consolidation, Less-than-Wholly-Owned Subsidiary, Parent Ownership Interest, Effect of Change [Table]
Restricted Stock and Restricted Stock Units [Member]
Represents information pertaining to restricted stock and restricted stock units.
2019 Equity Incentive Plan [Member]
Represents information pertaining to the "2019 Equity Incentive Plan".
ecd_Rule10b51ArrTrmntdFlag
Rule 10b5-1 Arrangement Terminated [Flag]
ecd_Rule10b51ArrAdoptedFlag
Rule 10b5-1 Arrangement Adopted [Flag]
Commitments and contingencies (Note 12)
alrs_DebtSecuritiesHeldtomaturityExcludingAccruedInterestAllowanceForCreditLossRecoveryWriteoff
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Allowance for Credit Loss, Recovery (Writeoff)
Amount, excluding accrued interest, of increase (decrease) in allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity) from recovery.
Bank of North Dakota [Member]
Represents information pertaining to the Bank of North Dakota.
Marketable Securities [Table Text Block]
Statistical Measurement [Axis]
srt_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Share Repurchase Program, Authorized, Number of Shares (in shares)
ecd_NonRule10b51ArrTrmntdFlag
Non-Rule 10b5-1 Arrangement Terminated [Flag]
Mortgage Banking [Member]
ecd_NonRule10b51ArrAdoptedFlag
Non-Rule 10b5-1 Arrangement Adopted [Flag]
Trading Arrangements, by Individual [Table]
Crossroads Branch in Rochester, Minnesota [Member]
Relating to Crossroads branch in Rochester, Minnesota.
New Stock Repurchase Program [Member]
Represents information pertaining to the "New Stock Repurchase Program".
Material Terms of Trading Arrangement [Text Block]
Deposit Account [Member]
Financial Instrument [Axis]
us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Unrealized Losses, Held-to-maturity
Unrealized Gains, Held-to-maturity
Minimum [Member]
us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Unrealized Losses, Available-for-sale
Unrealized Gains, Available-for-sale
alrs_PercentageOfIncreaseInFinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Percentage of Increase in Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest
The percentage of increase in amount, excluding accrued interest, of allowance for credit loss on financing receivable.
Statistical Measurement [Domain]
Maximum [Member]
Share Repurchase Program [Axis]
Share Repurchase Program [Domain]
us-gaap_EffectiveIncomeTaxRateContinuingOperations
Applicable income taxes, Percentage
Taxes at statutory federal income tax rate, Percentage
Retirement and Benefit Services Segment [Member]
Represents information pertaining to the retirement and benefit services segment.
Banking Segment [Member]
Represents information pertaining to the banking segment.
Compensation
Compensation
Financial Instruments [Domain]
Dividends declared per common share (in dollars per share)
Wealth Management Segment [Member]
Represents information pertaining to the wealth management segment.
Asset Pledged as Collateral [Member]
Weighted Average [Member]
State income taxes, net of federal benefits, Percentage
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer
us-gaap_EffectiveIncomeTaxRateReconciliationTaxExemptIncome
Tax exempt income, Percentage
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months
Award Type [Axis]
Adjustments to reconcile net income to net cash provided (used) by operating activities
Construction, Land, and Development [Member]
Represents information pertaining to the construction, land, and development loans.
Plan Name [Axis]
Non-Owner Occupied [Member]
Represents the information pertaining to non-owner occupied loans.
Plan Name [Domain]
Multifamily Loan [Member]
Represents information pertaining to multifamily loans.
Long-Term Debt, Adjustment, Variable Rate
Percentage points adjusted to the reference rate to compute the variable rate on a debt instrument.
us-gaap_AllocatedShareBasedCompensationExpense
Share-Based Payment Arrangement, Expense
Consolidation Items [Axis]
Real Estate, Junior Lien [Member]
Represents information pertaining to junior liens on real estate loans.
Visa [Member]
Represents information pertaining to visa.
alrs_InvestmentOwnedConversionRatio
Investment Owned, Conversion Ratio
Conversion ratio for investments owned.
Agricultural Real Estate Portfolio Segment [Member]
Represents information pertaining to the portfolio segment of the company's total financing receivables related to agricultural real estate.
Owner Occupied Loans [Member]
Represents the information pertaining to owner occupied loans.
Real Estate, First Lien [Member]
Represents information pertaining to first liens on real estate loans.
Production Loans [Member]
Represents information pertaining to production loans.
Preferred Class B [Member]
FHLB Borrowings, Deposits, and Other [Member]
Represents information pertaining to FHLB borrowings, deposits, and other borrowings.
us-gaap_ShareBasedCompensation
Share-based compensation expense
Consolidation Items [Domain]
Dividends and undistributed earnings allocated to participating securities
Net change in unrealized gain (losses) on cash flow hedging derivatives
Collateral, Other [Member]
Represents information pertaining collateral categorized as other.
Federal Home Loan Bank of Des Moines [Member]
Interest rate swaps, Gains/(Loss) Recognized in OCI
Change in fair value, after-tax amount
us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax
Change in fair value, tax expense (benefit)
Preferred Class A [Member]
Share-Based Payment Arrangement [Text Block]
us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax
Change in fair value, pre-tax amount
us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax
Less: reclassified AOCI gain (loss) into interest expense (3), tax expense (benefit)
Foreclosed assets
Represents the fair value of foreclosed assets.
us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax
Less: reclassified AOCI gain (loss) into interest expense (3), pre-tax amount
Interest rate swaps, Gain/(Loss) Reclassified from OCI into Earnings
Less: reclassified AOCI gain (loss) into interest expense (3), after-tax amount
Preferred stock, shares issued (in shares)
Preferred stock, shares outstanding (in shares)
us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTaxParent
Net change, pre-tax amount
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Preferred stock, shares authorized (in shares)
Portion at Fair Value Measurement [Member]
Net change in unrealized gain (losses) on other derivatives
alrs_BankOwnedLifeInsuranceFairValueDisclosure
Bank-owned life insurance
Fair value portion of bank owned life insurance.
Reported Value Measurement [Member]
alrs_InterestReceivableFairValueDisclosure
Accrued interest receivable
Fair value portion of interest receivable.
us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax
Change in fair value, after-tax amount
us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTaxParent
Net change, tax expense (benefit)
Preferred stock, par value (in dollars per share)
Collateral dependent loans, measurement input
Value of input used to measure impaired asset.
Collateral dependent loans, fair value
Represents the fair value of impaired loans.
us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent
Net change, after-tax amount
alrs_InterestbearingDepositsFairValueDisclosure
Interest-bearing deposits
Fair value portion of interest-bearing deposits.
us-gaap_CashAndCashEquivalentsFairValueDisclosure
Cash and cash equivalents
alrs_NoninterestbearingDepositsFairValueDisclosure
Noninterest-bearing deposits
Fair value portion of noninterest-bearing deposits.
AOCI, Derivative Qualifying as Hedge, Excluded Component, Parent [Member]
Estimate of Fair Value Measurement [Member]
alrs_InterestPayableFairValueDisclosure
Accrued interest payable
Fair value portion of interest receivable.
alrs_TimeDepositsFairValueDisclosure
Time deposits
Fair value portion of time deposits.
us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax
Change in fair value, tax expense (benefit)
Lessee, Operating and Finance Leases [Text Block]
The entire disclosure for operating and finance leases for the lessee.
Assets and Liabilities, Lessee [Table Text Block]
Tabular disclosure of lessee's assets and liabilities.
Forward Loan Sales Commitments [Member]
Represents information pertaining to forward loan sales commitments.
Statement [Table]
To-be-announced Mortgage Backed Securities [Member]
Represents information pertaining to mortgage backed securities to be announced.
Credit Facility [Axis]
Interest and Fee Income, Loans and Leases [Member]
Represents information pertaining to the interest and fee income from loans and leases.
Credit Facility [Domain]
us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAndTax
Change in fair value, pre-tax amount
Interest Income, Securities, Operating, Taxable [Member]
Represents information pertaining to taxable, operating interest income from securities.
Accrued expenses and other liabilities
us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss
Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block]
us-gaap_LoansReceivableFairValueDisclosure
Loans, net
Debt Securities, Available-for-Sale, Unrealized Loss Position
Interest Expense, Short-Term Borrowings [Member]
Represents information pertaining to the interest expense from short-term borrowings.
Collateral dependent loans
Equipment [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions
Financing Receivable, Collateral Dependant [Table Text Block]
The entire tabular disclosure for collateral dependent financing receivables.
Schedule Of Offsetting Derivative Assets And Liabilities [Table Text Block]
Tabular disclosure of derivative assets and derivative liabilities that are subject to offsetting, including master netting arrangements.
Product and Service [Domain]
Product and Service [Axis]
Interest Rate Swap, By Customer [Member]
Represents information pertaining to interest rate swaps by customer.
Consolidated Entities [Axis]
Consolidated Entities [Domain]
Interest Rate Swap, By Dealer Bank [Member]
Represents information pertaining to interest rate swaps by dealer bank.
Interest Rate Swap, By Company [Member]
Represents information pertaining to interest rate swaps by company.
us-gaap_ContinuingInvolvementWithTransferredFinancialAssetsPrincipalAmountOutstanding
Continuing Involvement with Transferred Financial Assets, Principal Amount Outstanding
Deposits [Member]
Residential Mortgage-Backed Securities [Member]
Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Cumulative Effect, Period of Adoption [Axis]
Cumulative Effect, Period of Adoption [Domain]
Summary of Amortization Expense and Tax Benefit [Table Text Block]
Tabular disclosure of amortization expense and tax benefit.
Statement [Line Items]
Qualified Affordable Housing Projects [Member]
Represents information pertaining to qualified affordable housing projects.
us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization
Low income housing tax credit, amortization expense
us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestments
Low income housing tax credit
us-gaap_QualifiedAffordableHousingProjectInvestmentsCommitment
Low income housing tax credit
us-gaap_AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount
Low income housing tax credit, tax benefit recognized
Disposal Group Classification [Axis]
Foreclosed assets, measurement input
Value of input used for foreclosed assets.
Disposal Group Classification [Domain]
Proceeds from maturities of investment securities available-for-sale
Proceeds from maturities and paydowns of investment securities held-to-maturity
Subordinated Notes Payable [Member]
Represents information pertaining to subordinated notes payable.
alrs_LoansAndLeasesReceivablesImpairedTroubledDebtInterestIncome
Loans and Leases Receivables, Impaired, Troubled Debt, Interest Income
The gross interest income that would have been recorded in the period on troubled debt restructurings, if the loans had been current in accordance with their original terms and had been outstanding throughout the period or since origination, if held for part of the period.
Loans held for sale
Wealth Management [Member]
Represents information pertaining to wealth management.
Retirement and Benefit Services [Member]
Represents information pertaining to retirement and benefit services.
us-gaap_ProceedsFromSaleOfHeldToMaturitySecurities
Proceeds from Sale of Held-to-Maturity Securities
Junior Subordinated Debenture Trust I [Member]
Represents information pertaining to junior subordinated debenture trust one.
Junior Subordinated Debenture Trust II [Member]
Represents information pertaining to the junior subordinated debenture trust 2.
Federal Home Loan Bank Advances [Member]
Capitalization, Long-Term Debt [Table]
Net change in unrealized gains (losses) on debt securities
Net change, pre-tax amount
FHLB
Proceeds from sales of foreclosed assets
Share Repurchase Program [Table]
us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent
Total other comprehensive income (loss), before tax
Intangible Asset, Finite-Lived, Class [Axis]
Intangible Asset, Finite-Lived, Class [Domain]
us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent
Net change, tax expense (benefit)
Proceeds on loans held for sale
Financing Receivable Portfolio Segment [Axis]
Other comprehensive income (loss)
Other comprehensive income (loss), net of tax
Unfunded Loan Commitment [Member]
us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent
Net change, after-tax amount
Financing Receivable Portfolio Segment [Domain]
Home Equity Loan [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Valuation Techniques [Table Text Block]
Fair Value Measurements, Nonrecurring [Table Text Block]
Fair Value, Inputs, Level 2 [Member]
Fair Value, Inputs, Level 3 [Member]
Fair Value, Inputs, Level 1 [Member]
Real Estate [Member]
Financial Instrument Performance Status [Domain]
Financial Asset, Aging [Axis]
Land, premises and equipment, net
Total
Property, Plant and Equipment, Gross
Financial Instrument Performance Status [Axis]
Deferred income taxes, net
Financial Asset, Aging [Domain]
Provision for (recovery of) credit losses
Provision for (recovery of) credit losses
Provision for credit losses
Financial Asset, 30 to 59 Days Past Due [Member]
Furniture and Fixtures [Member]
Financial Asset, 60 to 89 Days Past Due [Member]
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Fair Value Disclosures [Text Block]
us-gaap_GainLossOnDerivativeInstrumentsNetPretax
Realized loss (gain) on derivative instruments
Fair Value, by Balance Sheet Grouping [Table Text Block]
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]
Consumer, Other [Member]
Secured Overnight Financing Rate (SOFR) [Member]
us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments
Amortization and accretion of premiums/discounts on investment securities
Consumer Borrower [Member]
Commercial Borrower [Member]
Type of Borrower [Axis]
Class of Financing Receivable, Type of Borrower [Domain]
Investment Program, Proportional Amortization Method, Elected [Text Block]
Collateral Held [Domain]
Collateral Held [Axis]
Nondeductible items and other, Percentage
The percentage of nondeductible expense and other reconciling items for income tax reconciliations.
us-gaap_GainLossOnSaleOfPropertyPlantEquipment
Realized loss (gain) on sale of premises and equipment
us-gaap_PaymentsToAcquireLifeInsurancePolicies
Purchases of BOLI
us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Less accumulated depreciation
alrs_DebtSecuritiesHeldtomaturityFairValue
Investment securities held-to-maturity
Represents held-to-maturity debt securities measured at fair value.
Nondeductible items and other
The nondeductible expense and other reconciling items for income tax reconciliations.
Accumulated other comprehensive income (loss)
us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Finite-Lived Intangible Assets, Accumulated Amortization
Cash dividends declared, not paid
The cash dividends that are declared but unpaid.
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Income before income taxes
Interest Income
Additional paid-in capital
Disposal Group, Held-for-Sale, Not Discontinued Operations [Member]
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)
us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Purchases of premises and equipment
Collateral Pledged [Member]
Weighted-average remaining term, years (Year)
Goodwill [Table]
us-gaap_OffBalanceSheetCreditLossLiability
Off-Balance-Sheet, Credit Loss, Liability
Employee taxes and benefits
Employee taxes and benefits
us-gaap_Depreciation
Depreciation
us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt
Purchases of investment securities available-for-sale
us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt
Proceeds from Sale of Debt Securities, Available-for-Sale
Operating Segments [Member]
Segments [Domain]
Accounting Standards Update and Change in Accounting Principle [Text Block]
Income Statement [Abstract]
us-gaap_OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal
Off-Balance-Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)
us-gaap_NumberOfOperatingSegments
Number of Operating Segments
us-gaap_NumberOfReportableSegments
Number of Reportable Segments
Income Tax Contingency [Table]
Intangible amortization expense
Intangible Asset, Finite-Lived, Amortization Expense
us-gaap_DebtSecuritiesHeldToMaturityNonaccrual
Debt Securities, Held-to-Maturity, Nonaccrual
Income Tax Disclosure [Text Block]
us-gaap_FinancingReceivableNonaccrualInterestIncome
Financing Receivable, Nonaccrual, Interest Income
us-gaap_DebtSecuritiesHeldToMaturityNonaccrualInterestIncome
Debt Securities, Held-to-Maturity, Nonaccrual, Interest Income
Asset-Backed Securities [Member]
Taxes at statutory federal income tax rate
us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue
(Increase) in value of bank-owned life insurance
Transfers and Servicing of Financial Assets [Text Block]
State income taxes, net of federal benefits
Loans and Leases Receivable Disclosure [Table]
Fair Value Hierarchy and NAV [Domain]
Measurement Frequency [Domain]
us-gaap_TransferToOtherRealEstate
Loan collateral transferred to foreclosed assets
us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation
Disposal Group, Including Discontinued Operation, Assets
Statement of Financial Position [Abstract]
us-gaap_IncomeTaxReconciliationTaxExemptIncome
Tax exempt income
Deposit Liability [Table]
us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit
Time Deposits, at or Above FDIC Insurance Limit
Income taxes paid
Prepayment speeds
Other assets
Discount rate
Fair Value, Nonrecurring [Member]
Fair Value, Recurring [Member]
Banking Regulation, Common Equity Tier 1 Risk-Based Capital, Actual
Banking Regulation, Common Equity Tier 1 Risk-Based Capital, Capital Adequacy, Minimum
us-gaap_PaymentsForRepurchaseOfCommonStock
Repurchase of common stock
us-gaap_IncreaseDecreaseInOtherOperatingAssets
Other assets
Banking Regulation, Common Equity Tier 1 Risk-Based Capital, Well Capitalized, Minimum
us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)
Bank-owned life insurance
Per Common Share Data
Antidilutive Security, Excluded EPS Calculation [Table]
Basic earnings per common share (in dollars per share)
Other intangible assets, net
Finite-Lived Intangible Assets, Net
Finite-Lived Intangible Assets, Gross
Financing Receivables [Text Block]
us-gaap_SubleaseIncome
Sublease income
us-gaap_DebtInstrumentCollateralAmount
Debt Instrument, Collateral Amount
Goodwill
us-gaap_PaymentsToAcquireFederalHomeLoanBankStock
Purchases of FHLB stock
Sales of FHLB stock
Investment [Table Text Block]
Residential Portfolio Segment [Member]
Operating lease cost
Consumer Portfolio Segment [Member]
Short-term lease cost
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Table]
us-gaap_LeaseCost
Net lease cost
Commercial Portfolio Segment [Member]
Business Combination [Domain]
Business Combination [Axis]
Doubtful [Member]
Performing Financial Instruments [Member]
Special Mention [Member]
Money market savings
Substandard [Member]
Pass [Member]
Interest-bearing demand
Income tax expense (benefit) related to items of other comprehensive income (loss)
Other comprehensive income (loss), tax expense (benefit)
Time deposits
Nonperforming Financial Instruments [Member]
Savings accounts
Valuation Approach and Technique [Axis]
Valuation Approach and Technique [Domain]
Valuation, Market Approach [Member]
us-gaap_InterestExpenseDeposits
Deposits
us-gaap_InterestExpenseOperating
Total interest expense
Retained earnings
Interest Expense
us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities
Accrued expenses and other liabilities
alrs_ProceedsFromCallsOfDebtSecuritiesAvailableforsale
Proceeds from Calls of Debt Securities, Available-for-Sale
Amount of cash inflow from call of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).
Class of Stock [Axis]
Class of Financing Receivable [Axis]
Class of Financing Receivable [Domain]
Cash Flow Hedging [Member]
Fair Value Hedging [Member]
us-gaap_InterestExpenseLongTermDebt
Long-term debt
Total amounts in the Consolidated Statements of Income, Short-term Borrowings
Short-term borrowings
Fair Value Disclosure, off-Balance-Sheet Risks, Amount, Liability
us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
Net interest income after provision for (recovery of) credit losses
us-gaap_DerivativeCollateralObligationToReturnCash
Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset
Derivative Instruments, Gain (Loss) [Table Text Block]
us-gaap_CollateralAlreadyPostedAggregateFairValue
Collateral Already Posted, Aggregate Fair Value
Property, Plant, and Equipment [Table]
Common stock, par value (in dollars per share)
Taxable
Not Designated as Hedging Instrument, Trading [Member]
Exempt from federal income taxes
Hedging Relationship [Axis]
Derivative Contract [Domain]
Long-Lived Asset, Class [Axis]
Designated as Hedging Instrument [Member]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]
Cash and cash equivalents
Other
us-gaap_OtherInterestAndDividendIncome
Investment securities
us-gaap_InvestmentOwnedBalanceShares
Investment Owned, Balance, Shares (in shares)
Schedule of Assumptions for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Table Text Block]
Investment Holdings [Table]
Accrued interest receivable
Interest Receivable
us-gaap_TaxBasisOfInvestmentsCostForIncomeTaxPurposes
Investment, Tax Basis, Cost
Interest paid
Interest Rate Swap [Member]
Interest Rate Lock Commitments [Member]
Schedule of Long-Term Debt Instruments [Table Text Block]
Interim Period, Costs Not Allocable [Domain]
Corporate Bond Securities [Member]
Purchase Agreement to Sell Branch in West Fargo, North Dakota [Member]
Represents information pertaining to the purchase agreement to sell the branch in West Fargo, North Dakota.
Deposit Liabilities, Type [Table Text Block]
us-gaap_DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss
us-gaap_StockholdersEquity
Total stockholders’ equity
Balance
Balance
Goodwill [Table Text Block]
us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax
Less: reclassification adjustment from amortization of securities transferred from AFS to HTM (1), after-tax amount
Schedule of Short-Term Debt [Table Text Block]
us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossBeforeTax
Less: reclassification adjustment from amortization of securities transferred from AFS to HTM (1), pre-tax amount
us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossTax
Less: reclassification adjustment from amortization of securities transferred from AFS to HTM (1), tax expense (benefit)
Operating lease right-of-use assets
us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss
Property, Plant, and Equipment [Table Text Block]
Revenue from Contract with Customer, Including Assessed Tax