Securities Available for Sale and Held to Maturity - Contractual Maturities of Available for Sale and Held to Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Securities Available for Sale, Amortized Cost [Abstract]
Due in one year or less	$ 21,066
Due after one year through five years	336,659
Due after five years through ten years	98,549
Due after ten years	9,670
Total amortized cost, before mortgage-backed securities	465,944
Mortgage-backed securities	2,396,032
Securities Available for Sale, Amortized Cost	2,861,976	$ 3,256,289
Securities Available for Sale, Estimated Fair Value [Abstract]
Due in one year or less	21,057
Due after one year through five years	317,550
Due after five years through ten years	88,969
Due after ten years	9,246
Total fair value, before mortgage-backed securities	436,822
Mortgage-backed securities	2,207,542
Total	2,644,364	3,238,877
Securities Held to Maturity, Amortized Cost [Abstract]
Due in one year or less	4,135
Due after one year through five years	1,185
Due after five years through ten years	0
Due after ten years	0
Total amortized cost, before mortgage-backed securities	5,320
Mortgage-backed securities	1,132,434
Securities Held to Maturity, Amortized Cost	1,137,754	342,537
Securities Held to Maturity, Estimated Fair Value [Abstract]
Due in one year or less	4,137
Due after one year through five years	1,201
Due after five years through ten years	0
Due after ten years	0
Total fair value, before mortgage-backed securities	5,338
Mortgage-backed securities	1,097,121
Total	$ 1,102,459	$ 353,511