Fair Value Measurements - Assets and Liabilities Recorded at Fair Value on Non-recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended				6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Real Estate Secured [Member]	Jun. 30, 2012 Real Estate Secured [Member]	Jun. 30, 2013 Real Estate Secured [Member]	Jun. 30, 2012 Real Estate Secured [Member]	Jun. 30, 2013 Personal non-credit card [Member]	Jun. 30, 2012 Personal non-credit card [Member]	Jun. 30, 2013 Personal non-credit card [Member]	Jun. 30, 2012 Personal non-credit card [Member]	Jun. 30, 2013 Receivables Held For Sale [Member]	Jun. 30, 2012 Receivables Held For Sale [Member]	Jun. 30, 2013 Receivables Held For Sale [Member]	Jun. 30, 2012 Receivables Held For Sale [Member]	Jun. 30, 2013 Real Estate Owned [Member]		Jun. 30, 2012 Real Estate Owned [Member]		Jun. 30, 2013 Real Estate Owned [Member]		Jun. 30, 2012 Real Estate Owned [Member]		Jun. 30, 2013 Level 1	Dec. 31, 2012 Level 1	Jun. 30, 2013 Level 2	Dec. 31, 2012 Level 2	Jun. 30, 2013 Level 3	Dec. 31, 2012 Level 3	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 1	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 1	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 1 Real Estate Secured [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 1 Real Estate Secured [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 1 Personal non-credit card [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 1 Personal non-credit card [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 1 Receivables Held For Sale [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 1 Receivables Held For Sale [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 1 Real Estate Owned [Member]		Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 1 Real Estate Owned [Member]		Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 2	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 2	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 2 Real Estate Secured [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 2 Real Estate Secured [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 2 Personal non-credit card [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 2 Personal non-credit card [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 2 Receivables Held For Sale [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 2 Receivables Held For Sale [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 2 Real Estate Owned [Member]		Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 2 Real Estate Owned [Member]		Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 3	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 3	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 3 Real Estate Secured [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 3 Real Estate Secured [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 3 Personal non-credit card [Member]	Dec. 31, 2012 Non-Recurring Fair Value Measurements [Member] Level 3 Personal non-credit card [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 3 Personal non-credit card [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 3 Receivables Held For Sale [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 3 Receivables Held For Sale [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Level 3 Real Estate Owned [Member]		Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Level 3 Real Estate Owned [Member]		Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Total	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Total	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Total Real Estate Secured [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Total Real Estate Secured [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Total Personal non-credit card [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Total Personal non-credit card [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Total Receivables Held For Sale [Member]	Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Total Receivables Held For Sale [Member]	Jun. 30, 2013 Non-Recurring Fair Value Measurements [Member] Total Real Estate Owned [Member]		Jun. 30, 2012 Non-Recurring Fair Value Measurements [Member] Total Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale																									$ 0	$ 0	$ 0	$ 0	$ 0	$ 0			$ 0	$ 0	$ 0	$ 0	$ 0	$ 0							$ 0	$ 0	$ 0	$ 0	$ 0	$ 0							$ 4,991	$ 3,287	$ 0	$ 3,181	$ 3,469	$ 4,991	$ 6,756							$ 4,991	$ 3,287	$ 0	$ 3,469	$ 4,991	$ 6,756
Real estate owned																																							0	[1]	0	[1]									333	[1]	253	[1]										0	[1]	0	[1]									333	[1]	253	[1]
Total assets at fair value on a non-recurring basis																															0	0											333	253											4,991	6,756												5,324	7,009
Total Gains (Losses)	$ 354	$ (1,686)	$ 791	$ (1,712)	$ 372	$ (1,349)	$ 908	$ (1,349)	$ 0	$ (310)	$ (82)	$ (310)	$ 372	$ (1,659)	$ 826	$ (1,659)	$ (18)	[1]	$ (27)	[1]	$ (35)	[1]	$ (53)	[1]

[1] Real estate owned is required to be reported on the balance sheet net of transactions costs. The real estate owned amounts in the table above reflect the fair value of the underlying asset unadjusted for transaction costs.