Investment Securities - HTM Debt Securities in Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	$ 13,652	$ 9,830
Unrealized Loss, Less than 12 Months	91	130
Fair Value, 12 Months or More	2,019,713	2,062,485
Unrealized Loss, 12 Months or More	422,162	395,293
Fair Value, Total	2,033,365	2,072,315
Unrealized Loss, Total	422,253	395,423
U.S. Treasuries
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	17,779	17,951
Unrealized Loss, 12 Months or More	2,093	1,914
Fair Value, Total	17,779	17,951
Unrealized Loss, Total	2,093	1,914
U.S. Government agencies & GSEs
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	82,379	83,363
Unrealized Loss, 12 Months or More	16,673	15,689
Fair Value, Total	82,379	83,363
Unrealized Loss, Total	16,673	15,689
State and political subdivisions
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	13,297	2,986
Unrealized Loss, Less than 12 Months	88	13
Fair Value, 12 Months or More	217,862	217,547
Unrealized Loss, 12 Months or More	52,714	50,424
Fair Value, Total	231,159	220,533
Unrealized Loss, Total	52,802	50,437
Residential MBS, Agency & GSEs
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	355	311
Unrealized Loss, Less than 12 Months	3	2
Fair Value, 12 Months or More	1,135,361	1,175,263
Unrealized Loss, 12 Months or More	223,436	206,342
Fair Value, Total	1,135,716	1,175,574
Unrealized Loss, Total	223,439	206,344
Commercial MBS, Agency & GSEs
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	0	6,533
Unrealized Loss, Less than 12 Months	0	115
Fair Value, 12 Months or More	554,114	555,861
Unrealized Loss, 12 Months or More	124,464	118,424
Fair Value, Total	554,114	562,394
Unrealized Loss, Total	124,464	118,539
Supranational entities
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	12,218	12,500
Unrealized Loss, 12 Months or More	2,782	2,500
Fair Value, Total	12,218	12,500
Unrealized Loss, Total	$ 2,782	$ 2,500