Loans and Allowance for Loan Losses - Accretable yield, or income expected to be collected (Details) $ in Thousands	12 Months Ended
Dec. 31, 2022 USD ($)
Loans and Allowance for Loan Losses
New loans purchased	$ 225
Accretion of income	(48)
Ending balance	$ 177

Amount, after allowance for credit loss, of accrued interest on financing receivable.

No definition available.

Name:	alrs_FinancingReceivableAccruedInterestAfterAllowanceForCreditLosses
Namespace Prefix:	alrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant