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, 2023	Dec. 31, 2022
Securities Available for Sale, Amortized Cost [Abstract]
Due in one year or less	$ 15,760
Due after one year through five years	381,512
Due after five years through ten years	6,339
Due after ten years	4,654
Total amortized cost, before mortgage-backed securities	408,265
Mortgage-backed securities	1,699,344
Securities Available for Sale, Amortized Cost	2,107,609	$ 2,270,709
Securities Available for Sale, Estimated Fair Value [Abstract]
Due in one year or less	15,415
Due after one year through five years	348,845
Due after five years through ten years	6,110
Due after ten years	4,408
Total fair value, before mortgage-backed securities	374,778
Mortgage-backed securities	1,497,105
Total	1,871,883	2,024,082
Securities Held to Maturity, Amortized Cost [Abstract]
Due in one year or less	1,180
Due after one year through five years	28,679
Due after five years through ten years	0
Due after ten years	0
Total amortized cost, before mortgage-backed securities	29,859
Mortgage-backed securities	1,428,806
Securities Held to Maturity, Amortized Cost	1,458,665	1,494,514
Securities Held to Maturity, Estimated Fair Value [Abstract]
Due in one year or less	1,181
Due after one year through five years	28,314
Due after five years through ten years	0
Due after ten years	0
Total fair value, before mortgage-backed securities	29,495
Mortgage-backed securities	1,336,882
Total	$ 1,366,377	$ 1,406,589