Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017		Dec. 31, 2017
Fees and Commissions, Mortgage Banking and Servicing		$ 43	[1]	$ 46	[2]	$ 138	[3]	$ 148	[4]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		293,381				293,381				$ 285,301
Mortgage Servicing Rights, Fair Value [Member]
Fees and Commissions, Mortgage Banking and Servicing	[5]	108		100		322		301
Principal Amount Outstanding of Loans Serviced For Third Parties		139,955				139,955				136,071
Unpaid Principal Balance of Outstanding Underlying MSRs Purchased						7,000		0
Unpaid Principal Balance of Outstanding Underlying MSRs Transferred						5,900
Principal Amount Sold on Loans Serviced for Third Parties						781		350
Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		144,786				144,786				139,920
Commercial Mortgage Servicing Rights [Member]
Fees and Commissions, Mortgage Banking and Servicing	[6]	5		6		20		17
Principal Amount Outstanding of Loans Serviced		32,245				32,245				30,054
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		6,039				6,039				5,760
Servicing Asset at Amortized Cost		64				64				65
Consumer Portfolio Segment [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		138,747				138,747				134,160
Pillar Financial [Member]
Fees and Commissions, Mortgage Banking and Servicing	[6]	3		$ 3		9		$ 11
Principal Amount Outstanding of Loans Serviced For Third Parties		$ 26,206				$ 26,206				$ 24,294

[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] Recognized in Mortgage servicing related income in the Consolidated Statements of Income.

[6] Recognized in Commercial real estate related income in the Consolidated Statements of Income.