Debt Securities Available-for-Sale - Mortgage-Backed Securities and Other Securities Available-for-Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 1,338,893	$ 1,129,777
Gross unrealized gains	9,370	1,366
Gross unrealized losses	(17,359)	(30,326)
Estimated fair value	1,330,904	1,100,817
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	607	75,734
Gross unrealized gains	0	0
Gross unrealized losses	(51)	(386)
Estimated fair value	556	75,348
Pass-through certificates, GSE
Debt Securities, Available-for-sale [Line Items]
Amortized cost	356,703	282,704
Gross unrealized gains	2,164	0
Gross unrealized losses	(12,330)	(21,028)
Estimated fair value	346,537	261,676
GSE
Debt Securities, Available-for-sale [Line Items]
Amortized cost	950,993	734,086
Gross unrealized gains	6,977	1,231
Gross unrealized losses	(4,612)	(7,974)
Estimated fair value	953,358	727,343
Real estate mortgage investment conduits (REMICs)
Debt Securities, Available-for-sale [Line Items]
Amortized cost	1,307,696	1,016,790
Gross unrealized gains	9,141	1,231
Gross unrealized losses	(16,942)	(29,002)
Estimated fair value	1,299,895	989,019
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized cost	484	684
Gross unrealized gains	0	1
Gross unrealized losses	0	0
Estimated fair value	484	685
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized cost	30,106	36,569
Gross unrealized gains	229	134
Gross unrealized losses	(366)	(938)
Estimated fair value	29,969	35,765
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	30,590	37,253
Gross unrealized gains	229	135
Gross unrealized losses	(366)	(938)
Estimated fair value	$ 30,453	$ 36,450