Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018		Mar. 31, 2017		Dec. 31, 2017
Bank Servicing Fees	$ 54	[1]	$ 58	[2]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	283,994				$ 285,301
Mortgage Servicing Rights, Fair Value [Member]
Bank Servicing Fees	107		101
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	164,700				165,500
Principal Amount Outstanding of Loans Serviced For Third Parties	135,300				136,100
Unpaid Principal Balance of Outstanding Underlying MSRs Purchased	5,900		0
Principal Amount Sold on Loans Serviced for Third Parties	102		64
Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	139,287				139,920
Commercial Mortgage Servicing Rights [Member]
Servicing Asset at Amortized Cost	64				65
Bank Servicing Fees	7		5
Principal Amount Outstanding of Loans Serviced	31,100				30,100
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	5,800				5,800
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	133,489				134,160
Pillar Financial [Member]
Bank Servicing Fees	3		$ 4
Principal Amount Outstanding of Loans Serviced For Third Parties	$ 25,300				$ 24,300

[1] Amounts are presented in accordance with ASC Topic 606, Revenue from Contracts with Customers.

[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.