Investment Securities - Schedule of Gross Unrealized Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Abstract]
Fair Value, Less than 12 months	$ 85,672	$ 646,226
Unrealized Loss, Less than 12 months	(2,915)	(67,665)
Fair Value, 12 months or more	1,184,926	793,685
Unrealized Loss, 12 months or more	(262,312)	(167,181)
Fair Value, Total	1,270,598	1,439,911
Unrealized Loss, Total	(265,227)	(234,846)
U.S. government agency securities
Debt Securities, Available-for-sale [Abstract]
Fair Value, Less than 12 months	16,401	23,791
Unrealized Loss, Less than 12 months	(23)	(2,802)
Fair Value, 12 months or more	13,606	16,271
Unrealized Loss, 12 months or more	(1,588)	(2,303)
Fair Value, Total	30,007	40,062
Unrealized Loss, Total	(1,611)	(5,105)
Mortgage-backed securities - residential
Debt Securities, Available-for-sale [Abstract]
Fair Value, Less than 12 months	0	316,656
Unrealized Loss, Less than 12 months	0	(32,470)
Fair Value, 12 months or more	871,074	717,537
Unrealized Loss, 12 months or more	(212,237)	(157,859)
Fair Value, Total	871,074	1,034,193
Unrealized Loss, Total	(212,237)	(190,329)
Mortgage-backed securities - commercial
Debt Securities, Available-for-sale [Abstract]
Fair Value, Less than 12 months	0	11,104
Unrealized Loss, Less than 12 months	0	(968)
Fair Value, 12 months or more	16,677	6,540
Unrealized Loss, 12 months or more	(1,840)	(597)
Fair Value, Total	16,677	17,644
Unrealized Loss, Total	(1,840)	(1,565)
Municipal securities
Debt Securities, Available-for-sale [Abstract]
Fair Value, Less than 12 months	69,271	196,419
Unrealized Loss, Less than 12 months	(2,892)	(26,811)
Fair Value, 12 months or more	173,513	36,726
Unrealized Loss, 12 months or more	(41,573)	(4,602)
Fair Value, Total	242,784	233,145
Unrealized Loss, Total	(44,465)	(31,413)
U.S. Treasury securities
Debt Securities, Available-for-sale [Abstract]
Fair Value, Less than 12 months	0	94,248
Unrealized Loss, Less than 12 months	0	(4,122)
Fair Value, 12 months or more	106,798	13,432
Unrealized Loss, 12 months or more	(4,832)	(1,499)
Fair Value, Total	106,798	107,680
Unrealized Loss, Total	(4,832)	(5,621)
Corporate securities
Debt Securities, Available-for-sale [Abstract]
Fair Value, Less than 12 months	0	4,008
Unrealized Loss, Less than 12 months	0	(492)
Fair Value, 12 months or more	3,258	3,179
Unrealized Loss, 12 months or more	(242)	(321)
Fair Value, Total	3,258	7,187
Unrealized Loss, Total	$ (242)	$ (813)