Borrowing Arrangements - Components (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Line of Credit Facility [Line Items]
Borrowings	$ 175,000	$ 73,000
Line of Credit | Unsecured Credit Lines
Line of Credit Facility [Line Items]
Total credit limit	150,000	110,000
Borrowings	0	0
Line of Credit | Federal Home Loan Bank Borrowings
Line of Credit Facility [Line Items]
Total credit limit	878,907	809,391
Borrowings	175,000	73,000
Letters of credit	0	27,000
Collateral pledged	1,929,752	1,446,828
Fair value of collateral	1,325,541	1,230,691
Line of Credit | Federal Reserve Bank
Line of Credit Facility [Line Items]
Borrowings	0	0
Line of Credit | Federal Reserve Bank | Federal Reserve Bank Advances
Line of Credit Facility [Line Items]
Total credit limit	3,101	3,411
Collateral pledged	3,600	3,910
Fair value of collateral	$ 3,204	$ 3,536