Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017		Dec. 31, 2017
Bank Servicing Fees		$ 40	[1]	$ 44	[2]	$ 95	[3]	$ 102	[4]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		291,364				291,364				$ 285,301
Mortgage Servicing Rights, Fair Value [Member]
Bank Servicing Fees	[5]	107		101		214		202
Principal Amount Outstanding of Loans Serviced For Third Parties		140,328				140,328				136,071
Unpaid Principal Balance of Outstanding Underlying MSRs Purchased						5,900		0
Principal Amount Sold on Loans Serviced for Third Parties						221		217
Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		144,479				144,479				139,920
Commercial Mortgage Servicing Rights [Member]
Servicing Asset at Amortized Cost		63				63				65
Bank Servicing Fees	[6]	7		6		14		11
Principal Amount Outstanding of Loans Serviced		31,892				31,892				30,054
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		5,894				5,894				5,760
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		138,585				138,585				134,160
Pillar Financial [Member]
Bank Servicing Fees	[6]	3		$ 4		6		$ 8
Principal Amount Outstanding of Loans Serviced For Third Parties		$ 25,998				$ 25,998				$ 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.