Securities Available for Sale and Held to Maturity - Contractual Maturities of Available for Sale and Held to Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Securities Available for Sale, Amortized Cost [Abstract]
Due in one year or less	$ 30,375
Due after one year through five years	382,241
Due after five years through ten years	53,155
Due after ten years	7,221
Total amortized cost, before mortgage-backed securities	472,992
Mortgage-backed securities	2,303,423
Securities Available for Sale, Amortized Cost	2,776,415	$ 3,256,289
Securities Available for Sale, Estimated Fair Value [Abstract]
Due in one year or less	30,163
Due after one year through five years	347,173
Due after five years through ten years	45,983
Due after ten years	6,838
Total fair value, before mortgage-backed securities	430,157
Mortgage-backed securities	2,014,329
Total	2,444,486	3,238,877
Securities Held to Maturity, Amortized Cost [Abstract]
Due in one year or less	4,171
Due after one year through five years	341
Due after five years through ten years	0
Due after ten years	0
Total amortized cost, before mortgage-backed securities	4,512
Mortgage-backed securities	1,152,473
Securities Held to Maturity, Amortized Cost	1,156,985	342,537
Securities Held to Maturity, Estimated Fair Value [Abstract]
Due in one year or less	4,167
Due after one year through five years	340
Due after five years through ten years	0
Due after ten years	0
Total fair value, before mortgage-backed securities	4,507
Mortgage-backed securities	1,061,321
Total	$ 1,065,828	$ 353,511