Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Bank Servicing Fees		$ 62		$ 43
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	[1]	261,753			$ 258,212
Servicing Asset at Fair Value, Amount		1,182			1,307
Mortgage Servicing Rights, Fair Value [Member]
Bank Servicing Fees		87		82
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement		148,900			148,200
Principal Amount Outstanding of Loans Serviced For Third Parties		121,300			121,000
Unpaid Principal Balance of Outstanding Underlying MSRs Purchased		8,100		6,100
Unpaid Principal Balance of Outstanding Underlying MSRs Transferred		1,800
Principal Amount Sold on Loans Serviced for Third Parties		221		215
Servicing Asset at Fair Value, Amount		1,182		1,181	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]	118,263			117,797
indirect auto loan servicing rights [Member]
Bank Servicing Fees		2		0
Servicing Asset			$ 13
Servicing Asset at Fair Value, Amount		7
Servicing Asset at Amortized Cost		7
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]	$ 729		$ 0	$ 807
Proceeds from Securitizations of Consumer Loans			$ 1,000

[1] Excludes $1.9 billion and $1.8 billion of LHFS at March 31, 2016 and December 31, 2015, respectively.