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Debt Securities Available-for-Sale - Comparative Summary of Mortgage-Backed Securities and Other Securities Available-for-Sale) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 1,130,384	$ 1,205,516
Gross unrealized gains	71	7,824
Gross unrealized losses	(43,587)	(5,103)
Estimated fair value	1,086,868	1,208,237
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	76,572	2,344
Gross unrealized gains	0	0
Gross unrealized losses	(1,769)	(54)
Estimated fair value	74,803	2,290
Real estate mortgage investment conduits (REMICs)
Debt Securities, Available-for-sale [Line Items]
Amortized cost	855,942	969,790
Gross unrealized gains	49	7,631
Gross unrealized losses	(34,752)	(4,305)
Estimated fair value	821,239	973,116
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	197,870	233,382
Gross unrealized gains	22	193
Gross unrealized losses	(7,066)	(744)
Estimated fair value	190,826	232,831
GSE | Pass-through Certificates
Debt Securities, Available-for-sale [Line Items]
Amortized cost	538,676	579,035
Gross unrealized gains	49	5,233
Gross unrealized losses	(25,299)	(2,862)
Estimated fair value	513,426	581,406
GSE | Real estate mortgage investment conduits (REMICs)
Debt Securities, Available-for-sale [Line Items]
Amortized cost	317,266	390,755
Gross unrealized gains	0	2,398
Gross unrealized losses	(9,453)	(1,443)
Estimated fair value	307,813	391,710
Municipal bonds | Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	52	71
Gross unrealized gains	0	1
Gross unrealized losses	0	0
Estimated fair value	52	72
Corporate bonds | Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	197,818	233,311
Gross unrealized gains	22	192
Gross unrealized losses	(7,066)	(744)
Estimated fair value	$ 190,774	$ 232,759

X

- Definition

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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