Loans and Allowances for Credit Losses, Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 249,460	$ 246,473	$ 235,704	$ 256,421
Provision for loan losses	19,957	(6,158)	34,482	(10,125)
Loans charged off	(8,049)	(1,368)	(11,716)	(9,173)
Recoveries of loans previously charged off	1,346	2,167	4,244	3,991
Ending balance	262,714	241,114	262,714	241,114
Provision Details [Abstract]
Provision for credit losses	17,000	0	33,000	0
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	62,943	36,245	60,919	32,977
Provision for off-balance sheet credit risk	(3,003)	6,005	(979)	9,273
Ending balance	59,940	42,250	59,940	42,250
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	23,105,408		23,105,408		$ 22,435,353
Individually measured for impairment, recorded investment	132,251		132,251		121,797
Total	23,237,659		23,237,659		22,557,150
Related allowance [Abstract]
Collectively measured for impairment, related allowance	253,348		253,348		230,134
Individually measured for impairment, related allowance	9,366		9,366		5,570
Total	262,714		262,714		235,704
Commercial [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	139,898	151,448	131,586	162,056
Provision for loan losses	5,420	(15,468)	11,750	(20,586)
Loans charged off	(2,797)	(6)	(2,809)	(6,087)
Recoveries of loans previously charged off	748	1,588	2,742	2,179
Ending balance	143,269	137,562	143,269	137,562
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	20,608	13,966	18,246	13,812
Provision for off-balance sheet credit risk	(314)	1,873	2,048	2,027
Ending balance	20,294	15,839	20,294	15,839
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	14,461,239		14,461,239		14,152,202
Individually measured for impairment, recorded investment	73,277		73,277		60,297
Total	14,534,516		14,534,516		14,212,499
Related allowance [Abstract]
Collectively measured for impairment, related allowance	135,453		135,453		127,566
Individually measured for impairment, related allowance	7,816		7,816		4,020
Total	143,269		143,269		131,586
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	66,003	58,974	57,648	58,553
Provision for loan losses	14,300	4,085	24,726	4,553
Loans charged off	(4,000)	(78)	(6,208)	(269)
Recoveries of loans previously charged off	44	16	181	160
Ending balance	76,347	62,997	76,347	62,997
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	40,211	20,465	40,490	17,442
Provision for off-balance sheet credit risk	(2,530)	4,205	(2,809)	7,228
Ending balance	37,681	24,670	37,681	24,670
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	4,953,406		4,953,406		4,590,207
Individually measured for impairment, recorded investment	17,395		17,395		16,570
Total	4,970,801		4,970,801		4,606,777
Related allowance [Abstract]
Collectively measured for impairment, related allowance	74,797		74,797		56,098
Individually measured for impairment, related allowance	1,550		1,550		1,550
Total	76,347		76,347		57,648
Loans to individuals [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	43,559	36,051	46,470	35,812
Provision for loan losses	237	5,225	(1,994)	5,908
Loans charged off	(1,252)	(1,284)	(2,699)	(2,817)
Recoveries of loans previously charged off	554	563	1,321	1,652
Ending balance	43,098	40,555	43,098	40,555
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	2,124	1,814	2,183	1,723
Provision for off-balance sheet credit risk	(159)	(73)	(218)	18
Ending balance	1,965	$ 1,741	1,965	$ 1,741
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	3,690,763		3,690,763		3,692,944
Individually measured for impairment, recorded investment	41,579		41,579		44,930
Total	3,732,342		3,732,342		3,737,874
Related allowance [Abstract]
Collectively measured for impairment, related allowance	43,098		43,098		46,470
Individually measured for impairment, related allowance	0		0		0
Total	$ 43,098		$ 43,098		$ 46,470