Note 29 - Fair Value of Assets and Liabilities (Details Textual) $ in Thousands	12 Months Ended
Dec. 31, 2024 USD ($)
Fair Value, Inputs, Level 3 [Member] \| Foreclosed Assets [Member] \| Measurement Input, Comparability Adjustment [Member] \| Valuation, Market Approach [Member]
Securities Received as Collateral, Amount Foreclosed, Discounts	$ 0

The fair value of discounts on collateral received that was taken through foreclosure due to default by the original transferor in lieu of collection of the secured receivable.

No definition available.

Name:	alrs_SecuritiesReceivedAsCollateralAmountForeclosedDiscounts
Namespace Prefix:	alrs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration