Tax Credit Investments - Tax credits (Details) - Proportional amortization - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Tax Credit Investments [Line items]
Investment	$ 17,906	$ 17,906
Unfunded Commitment	$ 7,010	$ 12,347

The amount of low income housing tax credit of unfunded commitment.

No definition available.

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