Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 509		$ 514		$ 1,002		$ 1,023
Service charges on deposit accounts	144	[1]	151	[2]	289	[3]	299	[4]
Fees and Commissions, Other	93	[1]	103	[2]	179	[3]	198	[4]
Fees and Commissions, Credit and Debit Cards	85	[1]	87	[2]	166	[3]	169	[4]
Investment Banking Revenue	167	[1]	147	[2]	298	[3]	314	[4]
Trading Gain (Loss)	53	[1]	46	[2]	95	[3]	97	[4]
Fees and Commissions, Fiduciary and Trust Activities	75	[1]	76	[2]	150	[3]	151	[4]
Investment Advisory, Management and Administrative Fees	73	[1]	70	[2]	145	[3]	139	[4]
Bank Servicing Fees	40	[1]	44	[2]	95	[3]	102	[4]
Fees and Commissions, Mortgage Banking	43	[1]	56	[2]	79	[3]	109	[4]
commercial real estate related income	18	[1]	24	[2]	42	[3]	44	[4]
Gain (Loss) on Sale of Securities, Net	0	[1]	1	[2]	1	[3]	1	[4]
Noninterest Income, Other Operating Income	38	[1]	22	[2]	87	[3]	51	[4]
Noninterest Income	829	[1]	827	[2],[5],[6]	1,626	[3]	1,674	[4],[7],[8]
Contract with Customer, Performance Obligation Satisfied in Previous Period	13				26
Excluded from Scope of ASC 606 - Consumer [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income	99		107		213		242
Excluded from Scope of ASC 606 - Wholesale [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income	233		230		440		451
Excluded from Scope of ASC 606 - Corporate Other [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income	12		24		29		42
In Scope of ASC 606 - Consumer [Member]
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	115	[1],[9]	122	[2],[10]	219	[3],[11]	225	[4],[12]
Fees and Commissions, Other	29	[1],[9]	33	[2],[10]	57	[3],[11]	64	[4],[12]
Fees and Commissions, Credit and Debit Cards	57	[1],[9]	60	[2],[10]	111	[3],[11]	114	[4],[12]
Investment Banking Revenue	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Trading Gain (Loss)	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Fees and Commissions, Fiduciary and Trust Activities	74	[1],[9]	74	[2],[10]	149	[3],[11]	149	[4],[12]
Investment Advisory, Management and Administrative Fees	73	[1],[9]	70	[2],[10]	143	[3],[11]	137	[4],[12]
Bank Servicing Fees	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Fees and Commissions, Mortgage Banking	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
commercial real estate related income	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Gain (Loss) on Sale of Securities, Net	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Noninterest Income, Other Operating Income	6	[1],[9]	7	[2],[10]	12	[3],[11]	14	[4],[12]
Noninterest Income	354	[1],[9]	366	[2],[10]	691	[3],[11]	703	[4],[12]
In Scope of ASC 606 - Wholesale [Member]
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	29	[1],[9]	29	[2],[10]	70	[3],[11]	74	[4],[12]
Fees and Commissions, Other	3	[1],[9]	3	[2],[10]	6	[3],[11]	6	[4],[12]
Fees and Commissions, Credit and Debit Cards	26	[1],[9]	27	[2],[10]	52	[3],[11]	54	[4],[12]
Investment Banking Revenue	97	[1],[9]	89	[2],[10]	181	[3],[11]	185	[4],[12]
Trading Gain (Loss)	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Fees and Commissions, Fiduciary and Trust Activities	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Investment Advisory, Management and Administrative Fees	0	[1],[9]	0	[2],[10]	2	[3],[11]	1	[4],[12]
Bank Servicing Fees	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Fees and Commissions, Mortgage Banking	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
commercial real estate related income	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Gain (Loss) on Sale of Securities, Net	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Noninterest Income, Other Operating Income	0	[1],[9]	0	[2],[10]	0	[3],[11]	0	[4],[12]
Noninterest Income	155	[1],[9]	148	[2],[10]	311	[3],[11]	320	[4],[12]
Excluded from Scope of ASC 606 [Member]
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	0	[1],[9],[13]	0	[2],[10],[14]	0	[3],[11],[15]	0	[4],[12],[16]
Fees and Commissions, Other	61	[1],[9],[13]	67	[2],[10],[14]	116	[3],[11],[15]	128	[4],[12],[16]
Fees and Commissions, Credit and Debit Cards	2	[1],[9],[13]	0	[2],[10],[14]	3	[3],[11],[15]	1	[4],[12],[16]
Investment Banking Revenue	70	[1],[9],[13]	58	[2],[10],[14]	117	[3],[11],[15]	129	[4],[12],[16]
Trading Gain (Loss)	53	[1],[9],[13]	46	[2],[10],[14]	95	[3],[11],[15]	97	[4],[12],[16]
Fees and Commissions, Fiduciary and Trust Activities	1	[1],[9],[13]	2	[2],[10],[14]	1	[3],[11],[15]	2	[4],[12],[16]
Investment Advisory, Management and Administrative Fees	0	[1],[9],[13]	0	[2],[10],[14]	0	[3],[11],[15]	1	[4],[12],[16]
Bank Servicing Fees	40	[1],[9],[13]	44	[2],[10],[14]	95	[3],[11],[15]	102	[4],[12],[16]
Fees and Commissions, Mortgage Banking	43	[1],[9],[13]	56	[2],[10],[14]	79	[3],[11],[15]	109	[4],[12],[16]
commercial real estate related income	18	[1],[9],[13]	24	[2],[10],[14]	42	[3],[11],[15]	44	[4],[12],[16]
Gain (Loss) on Sale of Securities, Net	0	[1],[9],[13]	1	[2],[10],[14]	1	[3],[11],[15]	1	[4],[12],[16]
Noninterest Income, Other Operating Income	32	[1],[9],[13]	15	[2],[10],[14]	75	[3],[11],[15]	37	[4],[12],[16]
Noninterest Income	$ 320	[1],[9],[13]	$ 313	[2],[10],[14]	$ 624	[3],[11],[15]	$ 651	[4],[12],[16]

[1] Amounts are presented in accordance with ASC Topic 606, Revenue from Contracts with Customers, except for out of scope amounts.

[2] Amounts for periods prior to January 1, 2018 are presented in accordance with ASC Topic 605, Revenue Recognition, and have not been restated to conform with ASC Topic 606, Revenue from Contracts with Customers.

[3] Amounts are presented in accordance with ASC Topic 606, Revenue from Contracts with Customers, except for out of scope amounts.

[4] Amounts for periods prior to January 1, 2018 are presented in accordance with ASC Topic 605, Revenue Recognition, and have not been restated to conform with ASC Topic 606, Revenue from Contracts with Customers.

[5] During the fourth quarter of 2017, the Company sold PAC, the results of which were previously reported within the Wholesale business segment. For all periods prior to January 1, 2018, PAC's financial results, including the gain on sale, have been transferred to Corporate Other for enhanced comparability of the Wholesale business segment excluding PAC.

[6] During the second quarter of 2018, certain of the Company's business banking clients were transferred from the Wholesale business segment to the Consumer business segment. For all periods prior to the second quarter of 2018, the corresponding financial results have been transferred to the Consumer business segment for comparability purposes.

[7] During the fourth quarter of 2017, the Company sold PAC, the results of which were previously reported within the Wholesale business segment. For all periods prior to January 1, 2018, PAC's financial results, including the gain on sale, have been transferred to Corporate Other for enhanced comparability of the Wholesale business segment excluding PAC.

[8] During the second quarter of 2018, certain of the Company's business banking clients were transferred from the Wholesale business segment to the Consumer business segment. For all periods prior to the second quarter of 2018, the corresponding financial results have been transferred to the Consumer business segment for comparability purposes.

[9] Consumer and Wholesale total noninterest income exclude $99 million and $233 million of out of scope noninterest income, respectively, which are included in the business segment results presented on a management accounting basis in Note 18, "Business Segment Reporting." Out of scope total noninterest income includes these amounts and includes ($12) million of Corporate Other noninterest income that is out of scope of ASC Topic 606.

[10] Consumer and Wholesale total noninterest income exclude $107 million and $230 million of out of scope noninterest income, respectively, which are included in the business segment results presented on a management accounting basis in Note 18, "Business Segment Reporting." Out of scope total noninterest income includes these amounts and includes ($24) million of Corporate Other noninterest income that is out of scope of ASC Topic 606.

[11] Consumer and Wholesale total noninterest income exclude $213 million and $440 million of out of scope noninterest income, respectively, which are included in the business segment results presented on a management accounting basis in Note 18, "Business Segment Reporting." Out of scope total noninterest income includes these amounts and includes ($29) million of Corporate Other noninterest income that is out of scope of ASC Topic 606.

[12] Consumer and Wholesale total noninterest income exclude $242 million and $451 million of out of scope noninterest income, respectively, which are included in the business segment results presented on a management accounting basis in Note 18, "Business Segment Reporting." Out of scope total noninterest income includes these amounts and includes ($42) million of Corporate Other noninterest income that is out of scope of ASC Topic 606.

[13] The Company presents out of scope noninterest income for the purpose of reconciling noninterest income amounts within the scope of ASC Topic 606 to noninterest income amounts presented on the Company's Consolidated Statements of Income.

[14] The Company presents out of scope noninterest income for the purpose of reconciling noninterest income amounts within the scope of ASC Topic 606 to noninterest income amounts presented on the Company's Consolidated Statements of Income.

[15] The Company presents out of scope noninterest income for the purpose of reconciling noninterest income amounts within the scope of ASC Topic 606 to noninterest income amounts presented on the Company's Consolidated Statements of Income.

[16] The Company presents out of scope noninterest income for the purpose of reconciling noninterest income amounts within the scope of ASC Topic 606 to noninterest income amounts presented on the Company's Consolidated Statements of Income.