Fair Value Measurements - Quantitative Information for Non-Recurring Fair Value Measurements (Detail) (USD $) In Millions, unless otherwise specified				6 Months Ended			12 Months Ended		6 Months Ended		12 Months Ended		6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended			6 Months Ended		12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2013 Level 3	Dec. 31, 2012 Level 3	Dec. 31, 2012 First Lien [Member] Non-Recurring Fair Value Measurements [Member] Level 3	Jun. 30, 2013 Real Estate Secured [Member]	Jun. 30, 2013 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Collateral Severity Rates [Member] Minimum [Member]		Dec. 31, 2012 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Collateral Severity Rates [Member] Minimum [Member]		Jun. 30, 2013 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Collateral Severity Rates [Member] Maximum [Member]		Dec. 31, 2012 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Collateral Severity Rates [Member] Maximum [Member]		Jun. 30, 2013 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Expenses Incurred through Collateral Disposition [Member] Minimum [Member]	Dec. 31, 2012 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Expenses Incurred through Collateral Disposition [Member] Minimum [Member]	Jun. 30, 2013 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Expenses Incurred through Collateral Disposition [Member] Maximum [Member]	Dec. 31, 2012 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Expenses Incurred through Collateral Disposition [Member] Maximum [Member]	Jun. 30, 2013 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Market Discount Rate [Member] Minimum [Member]	Dec. 31, 2012 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Market Discount Rate [Member] Minimum [Member]	Jun. 30, 2013 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Market Discount Rate [Member] Maximum [Member]	Dec. 31, 2012 Real Estate Secured [Member] Level 3 Third Party Appraisal Valuation [Member] Market Discount Rate [Member] Maximum [Member]	Jun. 30, 2013 Real Estate Secured [Member] Non-Recurring Fair Value Measurements [Member] Level 3	Jun. 30, 2012 Real Estate Secured [Member] Non-Recurring Fair Value Measurements [Member] Level 3	Jun. 30, 2013 Personal non-credit card [Member]	Jun. 30, 2013 Personal non-credit card [Member] Level 3 Third Party Appraisal Valuation [Member] Collateral Severity Rates [Member] Minimum [Member]	Dec. 31, 2012 Personal non-credit card [Member] Level 3 Third Party Appraisal Valuation [Member] Collateral Severity Rates [Member] Minimum [Member]	Jun. 30, 2013 Personal non-credit card [Member] Level 3 Third Party Appraisal Valuation [Member] Collateral Severity Rates [Member] Maximum [Member]	Dec. 31, 2012 Personal non-credit card [Member] Level 3 Third Party Appraisal Valuation [Member] Collateral Severity Rates [Member] Maximum [Member]	Jun. 30, 2013 Personal non-credit card [Member] Level 3 Third Party Appraisal Valuation [Member] Market Discount Rate [Member] Minimum [Member]	Dec. 31, 2012 Personal non-credit card [Member] Level 3 Third Party Appraisal Valuation [Member] Market Discount Rate [Member] Minimum [Member]	Jun. 30, 2013 Personal non-credit card [Member] Level 3 Third Party Appraisal Valuation [Member] Market Discount Rate [Member] Maximum [Member]	Dec. 31, 2012 Personal non-credit card [Member] Level 3 Third Party Appraisal Valuation [Member] Market Discount Rate [Member] Maximum [Member]	Jun. 30, 2013 Personal non-credit card [Member] Non-Recurring Fair Value Measurements [Member] Level 3	Dec. 31, 2012 Personal non-credit card [Member] Non-Recurring Fair Value Measurements [Member] Level 3	Jun. 30, 2012 Personal non-credit card [Member] Non-Recurring Fair Value Measurements [Member] Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Receivables held for sale carried at fair value:	$ 0	$ 0	$ 3,022																		$ 4,991	$ 3,287										$ 0	$ 3,181	$ 3,469
Valuation Techniques				Third party appraisal valuation based on estimated loss severities, including collateral values, cash flows and market discount rate																			Third party appraisal valuation based on estimated loss rates, cash flows and market discount rate
Range of Inputs					0.00%	[1]	0.00%	[1]	98.00%	[1]	92.00%	[1]	5.00%	5.00%	10.00%	10.00%	4.00%	10.00%	8.00%	15.00%				0.00%	13.00%	0.00%	19.00%	0.00%	10.00%	0.00%	15.00%

[1] The majority of the real estate secured receivables held for sale consider collateral value, among other items, in determining fair value. Collateral values are based on the most recently available broker's price opinion and the collateral loss severity rate averaged 31 percent and 37 percent at June 30, 2013 and December 31, 2012, respectively.