Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 15, 2016	Jun. 30, 2015
Bank Servicing Fees		$ 189	$ 169	$ 196
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		278,197	258,212
Servicing Asset at Fair Value, Amount		1,572	1,307
Mortgage Servicing Rights, Fair Value [Member]
Bank Servicing Fees		366	347	329
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		160,200	148,200
Principal Amount Outstanding of Loans Serviced For Third Parties		129,600	121,000
Unpaid Principal Balance of Outstanding Underlying MSRs Purchased		19,700	10,300
Unpaid Principal Balance of Outstanding Underlying MSRs Transferred		13,800	0
Principal Amount Sold on Loans Serviced for Third Parties		575	803
Servicing Asset at Fair Value, Amount		1,572	1,307	$ 1,206
Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]	131,914	117,797
indirect auto loan servicing rights [Member]
Bank Servicing Fees		7	5
Servicing Asset						$ 13
Servicing Asset at Fair Value, Amount		4	9
Commercial Mortgage Servicing Rights [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		4,800
Servicing Asset at Fair Value, Amount		$ 62
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets					$ 62
Finite-Lived Intangible Asset, Useful Life		7 years
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	[1]	$ 512	807
Proceeds from Securitizations of Consumer Loans			$ 1,000

[1] Excludes loans that have completed the foreclosure or short sale process (i.e., involuntary prepayments)