Allowance for Loan and Lease Losses and Credit Quality - Recorded Investment by Credit Risk Category (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	$ 33,510,752	$ 19,073,020
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	22,281,686	11,659,108
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	10,810,534	6,220,632
Commercial | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	8,876,779	2,908,313
Commercial | Lease financing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	2,594,373	2,530,163
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	11,229,066	7,413,912
Consumer | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	6,057,404	2,335,835
Consumer | Consumer installment
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	1,562,252	2,003,572
Consumer | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	3,609,410	3,074,505
Pass
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	32,622,425	18,626,268
Pass | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	21,493,776	11,306,388
Pass | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	10,307,229	5,955,713
Pass | Commercial | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	8,645,910	2,869,711
Pass | Commercial | Lease financing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	2,540,637	2,480,964
Pass | Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	11,128,649	7,319,880
Pass | Consumer | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	6,001,380	2,294,740
Pass | Consumer | Consumer installment
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	1,561,506	1,981,844
Pass | Consumer | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	3,565,763	3,043,296
Special Mention
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	489,406	205,010
Special Mention | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	486,579	196,355
Special Mention | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	309,440	158,296
Special Mention | Commercial | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	150,132	12,864
Special Mention | Commercial | Lease financing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	27,007	25,195
Special Mention | Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	2,827	8,655
Special Mention | Consumer | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	1,543	3,606
Special Mention | Consumer | Consumer installment
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	1,302
Special Mention | Consumer | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	1,284	3,747
Substandard
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	398,921	241,742
Substandard | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	301,331	156,365
Substandard | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	193,865	106,623
Substandard | Commercial | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	80,737	25,738
Substandard | Commercial | Lease financing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	26,729	24,004
Substandard | Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	97,590	85,377
Substandard | Consumer | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	54,481	37,489
Substandard | Consumer | Consumer installment
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	746	20,426
Substandard | Consumer | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	42,363	27,462
Doubtful
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	0
Doubtful | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	0
Doubtful | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	0
Doubtful | Commercial | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	0
Doubtful | Commercial | Lease financing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	0
Doubtful | Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	0
Doubtful | Consumer | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	0
Doubtful | Consumer | Consumer installment
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	0	0
Doubtful | Consumer | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and leases	$ 0	$ 0