Securities - Schedule of Information Regarding Securities with Unrealized Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Securities in an Unrealized Loss Position for Less than 12 Months
Fair value, AFS and HTM	$ 7,772	$ 478,793
Unrealized losses, AFS and HTM	308	33,147
Securities in an Unrealized Loss Position for More than 12 Months
Fair value, AFS and HTM	2,500,310	2,263,197
Unrealized losses, AFS and HTM	646,491	520,099
Total
Fair value, AFS and HTM	2,508,082	2,741,990
Unrealized losses, AFS and HTM	646,799	553,246
U.S. Treasuries
Securities in an Unrealized Loss Position for Less than 12 Months
Fair value, AFS	0	168,758
Unrealized losses, AFS	0	5,662
Securities in an Unrealized Loss Position for More than 12 Months
Fair value, AFS	170,859	0
Unrealized losses, AFS	3,834	0
Total
Fair Value, AFS	170,859	168,758
Unrealized losses, AFS	3,834	5,662
Government-sponsored enterprise securities
Securities in an Unrealized Loss Position for Less than 12 Months
Fair value, AFS	0	0
Unrealized losses, AFS	0	0
Securities in an Unrealized Loss Position for More than 12 Months
Fair value, AFS	56,904	57,456
Unrealized losses, AFS	15,058	14,501
Total
Fair Value, AFS	56,904	57,456
Unrealized losses, AFS	15,058	14,501
Mortgage-backed securities
Securities in an Unrealized Loss Position for Less than 12 Months
Fair value, AFS and HTM	1,974	221,006
Unrealized losses, AFS and HTM	12	18,215
Securities in an Unrealized Loss Position for More than 12 Months
Fair value, AFS and HTM	1,863,253	1,835,958
Unrealized losses, AFS and HTM	502,357	405,557
Total
Fair value, AFS and HTM	1,865,227	2,056,964
Unrealized losses, AFS and HTM	502,369	423,772
Corporate bonds
Securities in an Unrealized Loss Position for Less than 12 Months
Fair value, AFS	400	40,644
Unrealized losses, AFS	18	947
Securities in an Unrealized Loss Position for More than 12 Months
Fair value, AFS	16,045	886
Unrealized losses, AFS	1,462	114
Total
Fair Value, AFS	16,445	41,530
Unrealized losses, AFS	1,480	1,061
State and local governments
Securities in an Unrealized Loss Position for Less than 12 Months
Fair value, HTM	5,398	48,385
Unrealized losses, HTM	278	8,323
Securities in an Unrealized Loss Position for More than 12 Months
Fair value, HTM	393,249	368,897
Unrealized losses, HTM	123,780	99,927
Total
Fair value, HTM	398,647	417,282
Unrealized losses, HTM	$ 124,058	$ 108,250