Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020		Mar. 31, 2019	Dec. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 200,307		$ 180,424
Charge-offs	(13,453)		(10,527)
Recoveries	6,242		6,014
Provision/(provision credit) for loan losses	145,000		9,000
Ending Balance	444,490		184,911
Allowance - individually evaluated for impairment	25,263		27,806
Allowance - collectively evaluated for impairment	419,227		153,692
Individually evaluated for impairment	253,347		275,148
Collectively evaluated for impairment	33,124,956		27,638,617
Total loans, net of unearned income	33,378,303	[1]	27,990,048	$ 31,061,111	[1]
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	158,598
Allowance - individually evaluated for impairment				6,196
Allowance - collectively evaluated for impairment				151,554
Individually evaluated for impairment				84,001
Collectively evaluated for impairment				24,273,207
Commercial | C&I
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	122,486		98,947
Charge-offs	(6,751)		(3,101)
Recoveries	935		829
Provision/(provision credit) for loan losses	119,064		7,038
Ending Balance	254,516		103,713
Allowance - individually evaluated for impairment	11,401		3,437
Allowance - collectively evaluated for impairment	243,115		98,135
Individually evaluated for impairment	100,092		83,253
Collectively evaluated for impairment	22,024,338		17,056,034
Total loans, net of unearned income	22,124,430		17,176,112	20,051,091
Commercial | Commercial Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	36,112		31,311
Charge-offs	(581)		(434)
Recoveries	573		57
Provision/(provision credit) for loan losses	18,869		3,448
Ending Balance	47,625		34,382
Allowance - individually evaluated for impairment	0		0
Allowance - collectively evaluated for impairment	47,625		34,382
Individually evaluated for impairment	163		1,879
Collectively evaluated for impairment	4,639,529		3,936,727
Total loans, net of unearned income	4,639,692		3,946,943	4,337,017
Consumer | Consumer Real Estate (a)
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	28,443		37,439
Charge-offs	(2,310)		(2,804)
Recoveries	3,555		4,041
Provision/(provision credit) for loan losses	342		(4,522)
Ending Balance	123,022		34,154
Allowance - individually evaluated for impairment	13,394		23,923
Allowance - collectively evaluated for impairment	109,628		9,108
Individually evaluated for impairment	152,393		189,332
Collectively evaluated for impairment	5,966,990		6,141,585
Total loans, net of unearned income	6,119,383		6,360,763	6,177,139
Consumer | Credit Card and Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	13,266		12,727
Charge-offs	(3,811)		(4,188)
Recoveries	1,179		1,087
Provision/(provision credit) for loan losses	6,725		3,036
Ending Balance	19,327		12,662
Allowance - individually evaluated for impairment	468		446
Allowance - collectively evaluated for impairment	18,859		12,067
Individually evaluated for impairment	699		684
Collectively evaluated for impairment	494,099		504,271
Total loans, net of unearned income	494,798		506,230	$ 495,864
Cumulative Effect, Period Of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	106,394
Cumulative Effect, Period Of Adoption, Adjustment | Commercial | C&I
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	18,782
Cumulative Effect, Period Of Adoption, Adjustment | Commercial | Commercial Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	(7,348)
Cumulative Effect, Period Of Adoption, Adjustment | Consumer | Consumer Real Estate (a)
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	92,992
Cumulative Effect, Period Of Adoption, Adjustment | Consumer | Credit Card and Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 1,968
Purchased credit-impaired loans
Allowance for Loan and Lease Losses [Roll Forward]
Ending Balance			3,413
Total loans, net of unearned income			76,283
Purchased credit-impaired loans | Commercial | C&I
Allowance for Loan and Lease Losses [Roll Forward]
Ending Balance			2,141
Total loans, net of unearned income			36,825
Purchased credit-impaired loans | Commercial | Commercial Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Ending Balance			0
Total loans, net of unearned income			8,337
Purchased credit-impaired loans | Consumer | Consumer Real Estate (a)
Allowance for Loan and Lease Losses [Roll Forward]
Ending Balance			1,123
Total loans, net of unearned income			29,846
Purchased credit-impaired loans | Consumer | Credit Card and Other
Allowance for Loan and Lease Losses [Roll Forward]
Ending Balance			149
Total loans, net of unearned income			$ 1,275

[1] March 31, 2020 and December 31, 2019 include $20.8 million and $18.8 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate in process of foreclosure.