Borrowings - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Ratio of line of credit to eligible assets	45.00%
Alaska limit on borrowing, percent of total assets	35.00%	35.00%
Alaska limit on borrowing, total assets	$ 975,900,000	$ 929,300,000
Line of credit	$ 347,400,000
Ratio of line of credit to total assets	12.00%
Ratio of eligible assets to borrowing capacity	45.00%
Additional borrowing capacity	$ 1,250,000,000
Long-term FHLB advances	$ 13,700,000	14,100,000
Amortization period of FHLB advance	30 years
FHLB discount window advances outstanding	$ 0	0
BTFP advances, discount window	0
Interest paid (less than)	28,547,000	5,190,000	$ 3,813,000
Securities sold under repurchase agreements	0	0
Interest expense on deposits, borrowings and junior subordinated debentures	$ 28,695,000	$ 5,213,000	$ 3,779,000
Weighted average interest rate	4.24%	2.92%	2.90%
Minimum
Debt Instrument [Line Items]
Term of FHLB advances	18 years
Fixed rate of FHLB advance	1.23%
Maximum
Debt Instrument [Line Items]
Term of FHLB advances	20 years
Fixed rate of FHLB advance	3.25%
Note Agreement With Federal Reserve Bank
Debt Instrument [Line Items]
Loans pledged as collateral	$ 60,000,000
Interest paid (less than)	1,000	$ 1,000
Discount Window
Debt Instrument [Line Items]
Loans pledged as collateral	58,300,000
FHLB and Secured Debt
Debt Instrument [Line Items]
Interest expense on deposits, borrowings and junior subordinated debentures	1,800,000	$ 339,000	$ 320,000
Federal Reserve Bank's Bank Term Funding Program ("BTFP")
Debt Instrument [Line Items]
Loans pledged as collateral	$ 20,000,000