Debt Securities Available-for-Sale - Mortgage-Backed Securities and Other Securities Available-for-Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 1,387,943	$ 1,418,504
Gross unrealized gains	6,039	8,900
Gross unrealized losses	(15,480)	(14,985)
Estimated fair value	1,378,502	1,412,419
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	587	607
Gross unrealized gains	0	0
Gross unrealized losses	(48)	(49)
Estimated fair value	539	558
Pass-through certificates, GSE
Debt Securities, Available-for-sale [Line Items]
Amortized cost	454,004	515,162
Gross unrealized gains	1,104	2,508
Gross unrealized losses	(11,402)	(10,721)
Estimated fair value	443,706	506,949
GSE
Debt Securities, Available-for-sale [Line Items]
Amortized cost	885,039	870,020
Gross unrealized gains	4,726	6,123
Gross unrealized losses	(3,900)	(4,044)
Estimated fair value	885,865	872,099
REMICs:
Debt Securities, Available-for-sale [Line Items]
Amortized cost	1,339,043	1,385,182
Gross unrealized gains	5,830	8,631
Gross unrealized losses	(15,302)	(14,765)
Estimated fair value	1,329,571	1,379,048
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized cost	614	614
Gross unrealized gains	1	1
Gross unrealized losses	(1)	(1)
Estimated fair value	614	614
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized cost	47,699	32,101
Gross unrealized gains	208	268
Gross unrealized losses	(129)	(170)
Estimated fair value	47,778	32,199
Other debt securities:
Debt Securities, Available-for-sale [Line Items]
Amortized cost	48,313	32,715
Gross unrealized gains	209	269
Gross unrealized losses	(130)	(171)
Estimated fair value	$ 48,392	$ 32,813

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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