Borrowings - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
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	$ 1,060,000,000.00	$ 975,900,000
Line of credit	$ 331,100,000
Ratio of line of credit to total assets	11.00%
Ratio of eligible assets to borrowing capacity	45.00%
Additional borrowing capacity	$ 1,360,000,000
Long-term FHLB advances	$ 13,200,000	13,700,000
Amortization period of FHLB advance	30 years
Short-term FHLB advances	$ 9,800,000
Short-term FHLB advances interest rate	4.62%
FHLB discount window advances outstanding	$ 0	0
Interest paid (less than)	40,482,000	28,547,000	$ 5,190,000
Securities sold under repurchase agreements	0	0
Interest expense	$ 40,736,000	$ 28,695,000	$ 5,213,000
Weighted average interest rate	3.13%	2.93%	2.92%
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	$ 70,000,000
Interest paid (less than)	1,000	$ 1,000
Discount Window
Debt Instrument [Line Items]
Loans pledged as collateral	68,500,000
FHLB and Secured Debt
Debt Instrument [Line Items]
Interest expense	$ 1,000,000.0	$ 1,800,000	$ 339,000