Loans and ACL - Risk Rating (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable
Loans and leases	$ 314,825	$ 299,842
2020	45,830
2019	60,815
2018	40,326
2017	26,376
2016	18,554
Prior	49,360
Revolving Credit	72,316
Loans Converted to Term	1,946
Other (1)	(698)
Credit card
Financing Receivable
Loans and leases	4,856
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Credit	4,816
Loans Converted to Term	37
Other (1)	3
Commercial: | Commercial & Industrial
Financing Receivable
Loans and leases	147,141	130,180
2020	26,295
2019	23,322
2018	15,991
2017	10,063
2016	6,287
Prior	11,925
Revolving Credit	54,285
Loans Converted to Term	14
Other (1)	(1,041)
Commercial: | Commercial & Industrial | Pass
Financing Receivable
Loans and leases	139,957	127,229
2020	25,664
2019	22,605
2018	15,180
2017	9,756
2016	5,963
Prior	11,545
Revolving Credit	50,186
Loans Converted to Term	10
Other (1)	(952)
Commercial: | Commercial & Industrial | Special mention
Financing Receivable
Loans and leases	3,879	1,264
2020	381
2019	408
2018	365
2017	74
2016	211
Prior	119
Revolving Credit	2,321
Loans Converted to Term	1
Other (1)	(1)
Commercial: | Commercial & Industrial | Substandard
Financing Receivable
Loans and leases	2,877	1,475
2020	220
2019	233
2018	306
2017	161
2016	93
Prior	248
Revolving Credit	1,612
Loans Converted to Term	1
Other (1)	3
Commercial: | Commercial & Industrial | Nonperforming
Financing Receivable
Loans and leases	428	212
2020	30
2019	76
2018	140
2017	72
2016	20
Prior	13
Revolving Credit	166
Loans Converted to Term	2
Other (1)	(91)
Commercial: | CRE
Financing Receivable
Loans and leases	27,963	26,832
2020	3,413
2019	8,364
2018	6,225
2017	3,487
2016	2,159
Prior	3,645
Revolving Credit	753
Loans Converted to Term	0
Other (1)	(83)
Commercial: | CRE | Pass
Financing Receivable
Loans and leases	25,079	26,393
2020	3,229
2019	7,609
2018	5,481
2017	3,123
2016	1,838
Prior	3,135
Revolving Credit	747
Loans Converted to Term	0
Other (1)	(83)
Commercial: | CRE | Special mention
Financing Receivable
Loans and leases	1,754	145
2020	118
2019	557
2018	512
2017	163
2016	180
Prior	219
Revolving Credit	5
Loans Converted to Term	0
Other (1)	0
Commercial: | CRE | Substandard
Financing Receivable
Loans and leases	1,088	284
2020	66
2019	195
2018	230
2017	198
2016	132
Prior	267
Revolving Credit	0
Loans Converted to Term	0
Other (1)	0
Commercial: | CRE | Nonperforming
Financing Receivable
Loans and leases	42	10
2020	0
2019	3
2018	2
2017	3
2016	9
Prior	24
Revolving Credit	1
Loans Converted to Term	0
Other (1)	0
Commercial: | Commercial construction
Financing Receivable
Loans and leases	6,891	6,205
2020	624
2019	2,050
2018	2,352
2017	705
2016	153
Prior	355
Revolving Credit	646
Loans Converted to Term	0
Other (1)	6
Commercial: | Commercial construction | Pass
Financing Receivable
Loans and leases	6,088	6,037
2020	601
2019	1,885
2018	1,972
2017	595
2016	75
Prior	299
Revolving Credit	642
Loans Converted to Term	0
Other (1)	19
Commercial: | Commercial construction | Special mention
Financing Receivable
Loans and leases	235	37
2020	16
2019	26
2018	141
2017	40
2016	11
Prior	1
Revolving Credit	0
Loans Converted to Term	0
Other (1)	0
Commercial: | Commercial construction | Substandard
Financing Receivable
Loans and leases	555	131
2020	7
2019	137
2018	229
2017	59
2016	67
Prior	55
Revolving Credit	1
Loans Converted to Term	0
Other (1)	0
Commercial: | Commercial construction | Nonperforming
Financing Receivable
Loans and leases	13	0
2020	0
2019	2
2018	10
2017	11
2016	0
Prior	0
Revolving Credit	3
Loans Converted to Term	0
Other (1)	(13)
Commercial: | Lease Financing
Financing Receivable
Loans and leases	5,783	6,122
2020	612
2019	1,678
2018	1,063
2017	1,065
2016	332
Prior	1,178
Revolving Credit	0
Loans Converted to Term	0
Other (1)	(145)
Commercial: | Lease Financing | Pass
Financing Receivable
Loans and leases	5,641	6,039
2020	609
2019	1,656
2018	1,056
2017	993
2016	323
Prior	1,131
Revolving Credit	0
Loans Converted to Term	0
Other (1)	(127)
Commercial: | Lease Financing | Special mention
Financing Receivable
Loans and leases	30	19
2020	3
2019	12
2018	3
2017	2
2016	4
Prior	6
Revolving Credit	0
Loans Converted to Term	0
Other (1)	0
Commercial: | Lease Financing | Substandard
Financing Receivable
Loans and leases	56	56
2020	0
2019	10
2018	4
2017	7
2016	2
Prior	33
Revolving Credit	0
Loans Converted to Term	0
Other (1)	0
Commercial: | Lease Financing | Nonperforming
Financing Receivable
Loans and leases	56	8
2020	0
2019	0
2018	0
2017	63
2016	3
Prior	8
Revolving Credit	0
Loans Converted to Term	0
Other (1)	(18)
Consumer: | Residential Mortgage
Financing Receivable
Loans and leases	51,671	52,071
2020	4,985
2019	7,835
2018	4,771
2017	5,497
2016	6,476
Prior	21,812
Revolving Credit	0
Loans Converted to Term	0
Other (1)	295
Consumer: | Residential Mortgage | Performing
Financing Receivable
Loans and leases	51,473	52,016
2020	4,985
2019	7,833
2018	4,765
2017	5,493
2016	6,468
Prior	21,634
Revolving Credit	0
Loans Converted to Term	0
Other (1)	295
Consumer: | Residential Mortgage | Nonperforming
Financing Receivable
Loans and leases	198	55
2020	0
2019	2
2018	6
2017	4
2016	8
Prior	178
Revolving Credit	0
Loans Converted to Term	0
Other (1)	0
Consumer: | Residential home equity and direct
Financing Receivable
Loans and leases	26,935	27,044
2020	2,875
2019	4,996
2018	2,703
2017	1,327
2016	788
Prior	1,668
Revolving Credit	10,643
Loans Converted to Term	1,895
Other (1)	40
Consumer: | Residential home equity and direct | Performing
Financing Receivable
Loans and leases	26,743	26,977
2020	2,875
2019	4,991
2018	2,698
2017	1,323
2016	784
Prior	1,667
Revolving Credit	10,576
Loans Converted to Term	1,811
Other (1)	18
Consumer: | Residential home equity and direct | Nonperforming
Financing Receivable
Loans and leases	192	67
2020	0
2019	5
2018	5
2017	4
2016	4
Prior	1
Revolving Credit	67
Loans Converted to Term	84
Other (1)	22
Consumer: | Indirect auto
Financing Receivable
Loans and leases	24,509	24,442
2020	4,208
2019	8,623
2018	4,894
2017	3,056
2016	1,719
Prior	892
Revolving Credit	978
Loans Converted to Term	0
Other (1)	139
Consumer: | Indirect auto | Performing
Financing Receivable
Loans and leases	24,354	24,342
2020	4,206
2019	8,581
2018	4,850
2017	3,026
2016	1,699
Prior	878
Revolving Credit	976
Loans Converted to Term	0
Other (1)	138
Consumer: | Indirect auto | Nonperforming
Financing Receivable
Loans and leases	155	100
2020	2
2019	42
2018	44
2017	30
2016	20
Prior	14
Revolving Credit	2
Loans Converted to Term	0
Other (1)	1
Consumer: | Indirect Other
Financing Receivable
Loans and leases	11,592	11,100
2020	2,792
2019	3,829
2018	2,222
2017	1,089
2016	569
Prior	808
Revolving Credit	195
Loans Converted to Term	0
Other (1)	88
Consumer: | Indirect Other | Performing
Financing Receivable
Loans and leases	11,589	11,098
2020	2,792
2019	3,828
2018	2,222
2017	1,089
2016	569
Prior	806
Revolving Credit	195
Loans Converted to Term	0
Other (1)	88
Consumer: | Indirect Other | Nonperforming
Financing Receivable
Loans and leases	3	2
2020	0
2019	1
2018	0
2017	0
2016	0
Prior	2
Revolving Credit	0
Loans Converted to Term	0
Other (1)	0
Consumer: | Student
Financing Receivable
Loans and leases	7,484	$ 6,743
2020	26
2019	118
2018	105
2017	87
2016	71
Prior	7,077
Revolving Credit	0
Loans Converted to Term	0
Other (1)	0
Consumer: | Student | Performing
Financing Receivable
Loans and leases	7,484
2020	26
2019	118
2018	105
2017	87
2016	71
Prior	7,077
Revolving Credit	0
Loans Converted to Term	0
Other (1)	0
Consumer: | Student | Nonperforming
Financing Receivable
Loans and leases	0
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Credit	0
Loans Converted to Term	0
Other (1)	$ 0