Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred income tax assets
Net unrealized losses on investment securities available for sale and cash flow hedges	$ 348,712	$ 455,744
Allowance for credit losses	130,205	121,941
Lease liability	120,534	107,818
Employee benefits and deferred compensation	40,601	42,746
Net operating loss carryforwards	32,126	23,590
Tax credit carryforwards	15,532	14,553
FDIC Special Assessment	12,058	0
Unrealized losses on fair value hedges	7,480	11,101
Non-performing loan interest	5,877	2,695
Miscellaneous accrued expenses	5,659	5,125
Fair value of investment securities and loans	1,422	2,019
Other	7,423	6,585
Total gross deferred tax assets	727,629	793,917
Less valuation allowance	(26,184)	(19,114)
Total deferred tax assets	701,445	774,803
Deferred tax liabilities
Right-of-use asset	(114,529)	(102,945)
Purchase accounting intangibles	(23,276)	(15,224)
Excess tax over financial statement depreciation	(20,457)	(23,762)
Deferred loan costs	(16,810)	(15,901)
Unrealized gain on hedged liabilities	(7,480)	(11,101)
Prepaid expense	(6,917)	(4,947)
Other properties held for sale	(1,434)	(2,828)
Other	(3,640)	(2,778)
Total gross deferred tax liabilities	(194,543)	(179,486)
Net deferred tax asset	$ 506,902	$ 595,317