Credit Loss Reserves - Summarizes Changes in Credit Loss Reserves by Product/Class and Related Receivable Balance by Product (Detail) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2015		Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		$ 2,110		$ 2,997	$ 2,217		$ 3,273
Provision for credit losses		192	[1]	(197)	219	[1]	(195)
Charge-offs	[2]	(1,898)	[1]	(195)	(2,045)	[1]	(506)
Recoveries		4		87	17		120
Total net charge-offs		(1,894)		(108)	(2,028)		(386)
Credit loss reserves at end of period		408		2,692	408		2,692
Reserve components:
Collectively evaluated for impairment								$ 106		$ 376
Individually evaluated for impairment	[3]							288		2,264
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell								13		49
Receivables acquired with deteriorated credit quality								408	$ 2,217
Total credit loss reserves		2,110		2,997	2,217		3,273	408	2,217	2,692
Receivables:
Collectively evaluated for impairment								8,471		13,089
Individually evaluated for impairment	[3]							1,485		10,523
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell								341		850
Total receivables								10,307	22,670	24,473
First lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		1,839		2,526	1,898		2,777
Provision for credit losses		167	[1]	(115)	204	[1]	(139)
Charge-offs	[2]	(1,808)	[1]	(143)	(1,916)	[1]	(391)
Recoveries		2		28	14		49
Total net charge-offs		(1,806)		(115)	(1,902)		(342)
Credit loss reserves at end of period		200		2,296	200		2,296
Reserve components:
Collectively evaluated for impairment								57		299
Individually evaluated for impairment	[3]							129		1,946
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell								13		49
Total credit loss reserves		1,839		2,526	1,898		2,777	200	1,898	2,296
Receivables:
Collectively evaluated for impairment								7,105		11,279
Individually evaluated for impairment	[3]							806		9,575
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell								315		819
Total receivables								8,235	20,153	21,682
Second lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		271		471	319		496
Provision for credit losses		25	[1]	(69)	15	[1]	(39)
Charge-offs	[2]	(90)	[1]	(52)	(129)	[1]	(115)
Recoveries		2		46	3		54
Total net charge-offs		(88)		(6)	(126)		(61)
Credit loss reserves at end of period		208		396	208		396
Reserve components:
Collectively evaluated for impairment								49		77
Individually evaluated for impairment	[3]							159		318
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell								0		0
Total credit loss reserves		271		471	319		496	208	319	396
Receivables:
Collectively evaluated for impairment								1,366		1,810
Individually evaluated for impairment	[3]							679		948
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell								26		31
Total receivables								2,072	2,517	2,791
Personal non-credit card [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		0		0	0		0
Provision for credit losses		0	[1]	(13)	0	[1]	(17)
Charge-offs	[2]	0	[1]	0	0	[1]	0
Recoveries		0		13	0		17
Total net charge-offs		0		13	0		17
Credit loss reserves at end of period		0		0	0		0
Reserve components:
Collectively evaluated for impairment								0		0
Individually evaluated for impairment	[3]							0		0
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell								0		0
Total credit loss reserves		$ 0		$ 0	$ 0		$ 0	0	$ 0	0
Receivables:
Collectively evaluated for impairment								0		0
Individually evaluated for impairment	[3]							0		0
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell								0		0
Total receivables								0		0
Receivables Acquired with Deteriorated Credit Quality [Member]
Reserve components:
Receivables acquired with deteriorated credit quality								1		3
Receivables:
Receivables acquired with deteriorated credit quality								10		11
Receivables Acquired with Deteriorated Credit Quality [Member] | First lien [Member]
Reserve components:
Receivables acquired with deteriorated credit quality								1		2
Receivables:
Receivables acquired with deteriorated credit quality								9		9
Receivables Acquired with Deteriorated Credit Quality [Member] | Second lien [Member]
Reserve components:
Receivables acquired with deteriorated credit quality								0		1
Receivables:
Receivables acquired with deteriorated credit quality								1		2
Receivables Acquired with Deteriorated Credit Quality [Member] | Personal non-credit card [Member]
Reserve components:
Receivables acquired with deteriorated credit quality								0		0
Receivables:
Receivables acquired with deteriorated credit quality								$ 0		$ 0

[1] The provision for credit losses and charge-offs for real estate secured receivables during the three and six months ended June 30, 2015 includes $220 million related to the lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale in June 2015. See Note 5, "Receivables Held for Sale," for additional information. The provision for credit losses for real estate secured receivables during the six months ended June 30, 2015 was impacted by a release of approximately $19 million associated with a correction to our credit loss reserve calculation for a segment of our portfolio.

[2] For collateral dependent receivables that are transferred to held for sale, existing credit loss reserves at the time of transfer are recognized as a charge-off. We transferred to held for sale certain real estate secured receivables during the three and six months ended June 30, 2015 and 2014 and, accordingly, we recognized the existing credit loss reserves on these receivables as additional charge-off totaling $1,578 million and $1,593 million during the three and six months ended June 30, 2015 compared with $18 million and $38 million during the three and six months ended June 30, 2014, respectively.

[3] These amounts represent TDR Loans for which we evaluate reserves using a discounted cash flow methodology. Each loan is individually identified as a TDR Loan and then grouped together with other TDR Loans with similar characteristics. The discounted cash flow impairment analysis is then applied to these groups of TDR Loans. The receivable balance above excludes TDR Loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell which totaled $256 million and $544 million at June 30, 2015 and 2014, respectively. The reserve component above excludes credit loss reserves totaling $10 million and $34 million at June 30, 2015 and 2014, respectively, for TDR Loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell. These receivables and credit loss reserves are reflected within receivables and credit loss reserves carried at the lower of amortized cost or fair value of the collateral less cost to sell in the table above.