Long-Term Debt (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Long-Term Debt
Face Value	$ 60,310	$ 60,310
Carrying Amount	58,928	58,843
Subordinated notes payable
Long-Term Debt
Face Value	50,000	50,000
Carrying Amount	$ 50,000	$ 50,000
Fixed interest rate	3.50%	3.50%
Junior subordinated debenture (Trust I)
Long-Term Debt
Face Value	$ 4,124	$ 4,124
Carrying Amount	$ 3,571	$ 3,537
Interest Rate	0.26%	3.10%
Debt instrument, adjustment, variable rate	3.10%
Investment, Variable Interest Rate, Type [Extensible Enumeration]	alrs:ThreeMonthCmeSofrMember	alrs:ThreeMonthLiborMember
Period End Interest Rate	8.76%	7.82%
Junior subordinated debenture (Trust II)
Long-Term Debt
Face Value	$ 6,186	$ 6,186
Carrying Amount	$ 5,357	$ 5,306
Interest Rate	0.26%	1.80%
Debt instrument, adjustment, variable rate	1.80%
Investment, Variable Interest Rate, Type [Extensible Enumeration]	alrs:ThreeMonthCmeSofrMember	alrs:ThreeMonthLiborMember
Period End Interest Rate	7.47%	6.57%