Securities - Amortized Cost and Estimated Fair Value of Investments in Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Available for sale, Amortized Cost
Due in one year or less	$ 528
Due after one year through five years	21,668
Due after five years through ten years	96,779
Due after ten years	1,127,179
Total available-for-sale investment securities	1,246,154
MBS:	346,737
Amortized Cost	1,592,891	$ 2,655,594
Available for sale, Fair Value
Due in one year or less	529
Due after one year through five years	21,154
Due after five years through ten years	93,415
Due after ten years	980,651
Total available-for-sale investment securities	1,095,749
MBS:	328,813
Total	1,424,562	2,764,325
Held to maturity, Amortized Cost
Due in one year or less	125
Due after one year through five years	1,039
Due after five years through ten years	100,463
Due after ten years	912,047
Total held-to-maturity investment securities	1,013,674
Mortgage-backed securities	137,531
Amortized cost	1,151,205	90,780
Held to maturity, Fair Value
Due in one year or less	123
Due after one year through five years	1,016
Due after five years through ten years	94,140
Due after ten years	721,477
Total held-to-maturity investment securities	816,756
Mortgage-backed securities	126,566
Total	$ 943,322	$ 95,235