Allowance for Loan and Lease Losses and Credit Quality - Accruing and Non-accrual Loans and Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due
Current	$ 33,133,196	$ 18,868,291
30-89 Days Delinquent and Accruing	166,088	91,367
90 Days or More Delinquent and Accruing	29,660	7,444
Total Accruing	33,328,944	18,967,102
Nonaccrual	181,808	105,918
Total	33,510,752	19,073,020
Portfolios acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due
Current	261,082	3,639
30-89 Days Delinquent and Accruing	16,578	0
90 Days or More Delinquent and Accruing	16,052	178
Total Accruing	293,712	3,817
Nonaccrual	0	0
Total	293,712	3,817
Consumer
Financing Receivable, Recorded Investment, Past Due
Total	11,229,066	7,413,912
Consumer | Financial Asset Originated
Financing Receivable, Recorded Investment, Past Due
Current	11,027,919	7,285,705
30-89 Days Delinquent and Accruing	31,769	56,237
90 Days or More Delinquent and Accruing	892	4,624
Total Accruing	11,060,580	7,346,566
Nonaccrual	88,748	67,346
Total	11,149,328	7,413,912
Consumer | Residential mortgage
Financing Receivable, Recorded Investment, Past Due
Total	6,057,404	2,335,835
Consumer | Residential mortgage | Financial Asset Originated
Financing Receivable, Recorded Investment, Past Due
Current	5,919,947	2,291,435
30-89 Days Delinquent and Accruing	14,533	10,014
90 Days or More Delinquent and Accruing	886	1,275
Total Accruing	5,935,366	2,302,724
Nonaccrual	48,816	33,111
Total	5,984,182	2,335,835
Consumer | Consumer installment
Financing Receivable, Recorded Investment, Past Due
Total	1,562,252	2,003,572
Consumer | Consumer installment | Financial Asset Originated
Financing Receivable, Recorded Investment, Past Due
Current	1,557,320	1,951,302
30-89 Days Delinquent and Accruing	3,667	40,340
90 Days or More Delinquent and Accruing	6	3,349
Total Accruing	1,560,993	1,994,991
Nonaccrual	636	8,581
Total	1,561,629	2,003,572
Consumer | Home equity
Financing Receivable, Recorded Investment, Past Due
Total	3,609,410	3,074,505
Consumer | Home equity | Financial Asset Originated
Financing Receivable, Recorded Investment, Past Due
Current	3,550,652	3,042,968
30-89 Days Delinquent and Accruing	13,569	5,883
90 Days or More Delinquent and Accruing	0	0
Total Accruing	3,564,221	3,048,851
Nonaccrual	39,296	25,654
Total	3,603,517	3,074,505
Commercial
Financing Receivable, Recorded Investment, Past Due
Total	22,281,686	11,659,108
Commercial | Financial Asset Originated
Financing Receivable, Recorded Investment, Past Due
Current	21,844,195	11,578,947
30-89 Days Delinquent and Accruing	117,741	35,130
90 Days or More Delinquent and Accruing	12,716	2,642
Total Accruing	21,974,652	11,616,719
Nonaccrual	93,060	38,572
Total	22,067,712	11,655,291
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due
Total	10,810,534	6,220,632
Commercial | Commercial and industrial | Financial Asset Originated
Financing Receivable, Recorded Investment, Past Due
Current	10,615,519	6,176,341
30-89 Days Delinquent and Accruing	49,595	13,653
90 Days or More Delinquent and Accruing	2,241	760
Total Accruing	10,667,355	6,190,754
Nonaccrual	55,039	26,061
Total	10,722,394	6,216,815
Commercial | Commercial real estate
Financing Receivable, Recorded Investment, Past Due
Total	8,876,779	2,908,313
Commercial | Commercial real estate | Financial Asset Originated
Financing Receivable, Recorded Investment, Past Due
Current	8,677,350	2,903,795
30-89 Days Delinquent and Accruing	39,023	0
90 Days or More Delinquent and Accruing	8,054	0
Total Accruing	8,724,427	2,903,795
Nonaccrual	26,518	4,518
Total	8,750,945	2,908,313
Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due
Total	2,594,373	2,530,163
Commercial | Lease financing | Financial Asset Originated
Financing Receivable, Recorded Investment, Past Due
Current	2,551,326	2,498,811
30-89 Days Delinquent and Accruing	29,123	21,477
90 Days or More Delinquent and Accruing	2,421	1,882
Total Accruing	2,582,870	2,522,170
Nonaccrual	11,503	7,993
Total	$ 2,594,373	$ 2,530,163