Loans and Allowances for Credit Losses, Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 241,114	$ 311,890	$ 256,421	$ 388,640
Provision for loan losses	1,111	(27,395)	(9,014)	(74,229)
Loans charged off	(1,766)	(9,584)	(10,939)	(44,793)
Recoveries of loans previously charged off	1,309	1,769	5,300	7,062
Ending balance	241,768	276,680	241,768	276,680
Provision Details [Abstract]
Provision for credit losses	15,000	(23,000)	15,000	(83,000)
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	42,250	24,287	32,977	36,921
Provision for off-balance sheet credit risk	14,060	4,952	23,333	(7,682)
Ending balance	56,310	29,239	56,310	29,239
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	21,659,657		21,659,657		$ 20,071,621
Individually measured for impairment, recorded investment	130,800		130,800		134,059
Total	21,790,457		21,790,457		20,205,680
Related allowance [Abstract]
Collectively measured for impairment, related allowance	224,720		224,720		250,079
Individually measured for impairment, related allowance	17,048		17,048		6,342
Total	241,768		241,768		256,421
Commercial [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	137,562	198,303	162,056	254,934
Provision for loan losses	3,158	(15,996)	(17,428)	(44,331)
Loans charged off	(75)	(6,979)	(6,162)	(38,826)
Recoveries of loans previously charged off	721	832	2,900	4,383
Ending balance	141,366	176,160	141,366	176,160
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	15,839	10,094	13,812	14,422
Provision for off-balance sheet credit risk	939	2,772	2,966	(1,556)
Ending balance	16,778	12,866	16,778	12,866
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	13,532,016		13,532,016		12,432,361
Individually measured for impairment, recorded investment	75,670		75,670		74,104
Total	13,607,686		13,607,686		12,506,465
Related allowance [Abstract]
Collectively measured for impairment, related allowance	125,253		125,253		158,063
Individually measured for impairment, related allowance	16,113		16,113		3,993
Total	141,366		141,366		162,056
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	62,997	70,540	58,553	86,558
Provision for loan losses	(4,415)	(9,418)	138	(24,579)
Loans charged off	0	(1,422)	(269)	(2,485)
Recoveries of loans previously charged off	7	228	167	434
Ending balance	58,589	59,928	58,589	59,928
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	24,670	12,348	17,442	20,571
Provision for off-balance sheet credit risk	12,826	2,294	20,054	(5,929)
Ending balance	37,496	14,642	37,496	14,642
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	4,465,940		4,465,940		3,817,063
Individually measured for impairment, recorded investment	7,971		7,971		14,262
Total	4,473,911		4,473,911		3,831,325
Related allowance [Abstract]
Collectively measured for impairment, related allowance	57,654		57,654		56,204
Individually measured for impairment, related allowance	935		935		2,349
Total	58,589		58,589		58,553
Paycheck Protection Program [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0	0	0
Provision for loan losses	0	0	0	0
Loans charged off	0	0	0	0
Recoveries of loans previously charged off	0	0	0	0
Ending balance	0	0	0	0
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	0	0	0	0
Provision for off-balance sheet credit risk	0	0	0	0
Ending balance	0	0	0	0
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	20,233		20,233		276,341
Individually measured for impairment, recorded investment	0		0		0
Total	20,233		20,233		276,341
Related allowance [Abstract]
Collectively measured for impairment, related allowance	0		0		0
Individually measured for impairment, related allowance	0		0		0
Total	0		0		0
Loans to individuals [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	40,555	43,047	35,812	47,148
Provision for loan losses	2,368	(1,981)	8,276	(5,319)
Loans charged off	(1,691)	(1,183)	(4,508)	(3,482)
Recoveries of loans previously charged off	581	709	2,233	2,245
Ending balance	41,813	40,592	41,813	40,592
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	1,741	1,845	1,723	1,928
Provision for off-balance sheet credit risk	295	(114)	313	(197)
Ending balance	2,036	$ 1,731	2,036	$ 1,731
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	3,641,468		3,641,468		3,545,856
Individually measured for impairment, recorded investment	47,159		47,159		45,693
Total	3,688,627		3,688,627		3,591,549
Related allowance [Abstract]
Collectively measured for impairment, related allowance	41,813		41,813		35,812
Individually measured for impairment, related allowance	0		0		0
Total	$ 41,813		$ 41,813		$ 35,812