Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Proceeds from Securitizations of Consumer Loans	$ 1,000
Amortization of Intangible Assets and Impairment of Goodwill	7	$ 4	$ 13	$ 7
Bank Servicing Fees	30	45	73	99
Mortgage Servicing Rights, Fair Value [Member]
Bank Servicing Fees	83	81	166	160
Qualitative and Quantitative Information, Transferor's Continuing Involvement, Principal Amount Outstanding	145,500		145,500		$ 142,100
Principal Amount Outstanding of Loans Serviced For Third Parties	118,400		118,400		$ 115,500
Unpaid Principal Balance of Outstanding Underlying MSRs Purchased			10,300	5,900
Unpaid Principal Balance of Outstanding Underlying MSRs Transferred			6,100
Principal Amount Sold on Loans Serviced for Third Parties			407	439
indirect auto loan servicing rights [Member]
Bank Servicing Fees	1	$ 0	1	$ 0
Qualitative and Quantitative Information, Transferor's Continuing Involvement, Principal Amount Outstanding	976		976
Indirect Auto Loans [Member]
Servicing Asset	$ 13		$ 13