Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Bank Servicing Fees				$ 169	$ 196	$ 87
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]		$ 248,646	258,212	248,646
Servicing Asset at Fair Value, Amount			1,206	1,307	1,206
Mortgage Servicing Rights, Fair Value [Member]
Bank Servicing Fees				347	329	317
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement			142,100	148,200	142,100
Principal Amount Outstanding of Loans Serviced For Third Parties			115,500	121,000	115,500
Unpaid Principal Balance of Outstanding Underlying MSRs Purchased				10,300	10,900
Unpaid Principal Balance of Outstanding Underlying MSRs Transferred				10,300
Principal Amount Sold on Loans Serviced for Third Parties				803	878
Servicing Asset at Fair Value, Amount			1,206	1,307	1,206	$ 1,300
Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]		110,591	117,797	110,591
indirect auto loan servicing rights [Member]
Bank Servicing Fees			0	5	0
Servicing Asset		$ 13
Servicing Asset at Fair Value, Amount				9
Servicing Asset at Amortized Cost				9
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]		$ 0	$ 807	$ 0
Proceeds from Securitizations of Consumer Loans		$ 1,000

[1] Excludes $1.8 billion and $3.2 billion of LHFS at December 31, 2015 and 2014, respectively.