Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		$ 193	$ 190	$ 566	$ 563
Other sources of noninterest income		59	66	170	181
Total noninterest income		252	256	736	744
Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		106	93	299	278
Other sources of noninterest income		29	47	107	134
Total noninterest income		135	140	406	412
Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		25	30	74	90
Other sources of noninterest income		3	1	6	5
Total noninterest income		28	31	80	95
Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		62	67	193	195
Other sources of noninterest income		2	2	7	6
Total noninterest income		64	69	200	201
Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Other sources of noninterest income		25	16	50	36
Total noninterest income		25	16	50	36
Credit and Debit Card [Member]
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		71	67	198	195
Credit and Debit Card [Member] | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		60	55	168	162
Credit and Debit Card [Member] | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		11	11	28	30
Credit and Debit Card [Member] | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	1	2	3
Credit and Debit Card [Member] | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Service charges on deposit accounts
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		47	51	138	153
Service charges on deposit accounts | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		33	32	95	98
Service charges on deposit accounts | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		12	18	39	52
Service charges on deposit accounts | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		2	1	4	3
Service charges on deposit accounts | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Fiduciary income
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		51	53	157	154
Fiduciary income | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Fiduciary income | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Fiduciary income | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		51	53	157	154
Fiduciary income | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Commercial loan servicing fees
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	5	5	13	13
Commercial loan servicing fees | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	5	5	13	13
Commercial loan servicing fees | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0	0	0
Commercial loan servicing fees | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0	0	0
Commercial loan servicing fees | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[1]	0	0	0	0
Brokerage Commissions Revenue [Member]
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		5	7	17	21
Brokerage Commissions Revenue [Member] | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Brokerage Commissions Revenue [Member] | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Brokerage Commissions Revenue [Member] | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		5	7	17	21
Brokerage Commissions Revenue [Member] | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers		0	0	0	0
Other noninterest income
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	14	7	43	27
Other noninterest income | Commercial Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	8	1	23	5
Other noninterest income | Retail Bank
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	2	1	7	8
Other noninterest income | Wealth Management
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	4	5	13	14
Other noninterest income | Finance & Other
Segment Reporting, Revenue Reconciling Item
Total revenue from contracts with customers	[2]	$ 0	$ 0	$ 0	$ 0

[1] Included in commercial lending fees on the Consolidated Statements of Comprehensive Income.

[2] Excludes derivative, warrant and other miscellaneous income.