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								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2015		Dec. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period					$ 311				$ 2,217	$ 311		$ 2,217		$ 3,273
Provision for credit losses		$ 0	$ 572	$ 12	37	$ 13	$ 18	$ 192	27	621	[1]	250	[1]	(365)
Charge-offs	[2]									(938)	[1]	(2,181)	[1]	(854)
Recoveries										6		25		161
Total net charge-offs										(932)		(2,156)		(693)
Other														2
Credit loss reserves at end of period		0				311				0		311		2,217
Reserve components:
Collectively evaluated for impairment															$ 79		$ 227
Individually evaluated for impairment	[3]														220		1,957
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell															12		33
Total credit loss reserves		0			311	311			2,217	311		2,217		3,273	311		2,217
Receivables held for investment:
Collectively evaluated for impairment															7,558		11,949
Individually evaluated for impairment	[3]														1,272		10,028
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell															326		693
Total receivables held for investment															9,156	[4],[5]	22,670
First lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period					137				1,898	137		1,898		2,777
Provision for credit losses										107	[1]	223	[1]	(308)
Charge-offs	[2]									(247)	[1]	(2,004)	[1]	(657)
Recoveries										3		20		84
Total net charge-offs										(244)		(1,984)		(573)
Other														2
Credit loss reserves at end of period		0				137				0		137		1,898
Reserve components:
Collectively evaluated for impairment															40		153
Individually evaluated for impairment	[3]														85		1,713
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell															12		32
Total credit loss reserves		0			137	137			1,898	137		1,898		2,777	137		1,898
Receivables held for investment:
Collectively evaluated for impairment															6,363		10,356
Individually evaluated for impairment	[3]														640		9,133
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell															299		664
Total receivables held for investment															7,302		20,153
Second lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period					174				319	174		319		496
Provision for credit losses										514	[1]	27	[1]	(39)
Charge-offs	[2]									(691)	[1]	(177)	[1]	(197)
Recoveries										3		5		59
Total net charge-offs										(688)		(172)		(138)
Other														0
Credit loss reserves at end of period		0				174				0		174		319
Reserve components:
Collectively evaluated for impairment															39		74
Individually evaluated for impairment	[3]														135		244
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell															0		1
Total credit loss reserves		0			174	174			319	174		319		496	174		319
Receivables held for investment:
Collectively evaluated for impairment															1,195		1,593
Individually evaluated for impairment	[3]														632		895
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell															27		29
Total receivables held for investment															1,854		2,517
Personal Non-Credit Card [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period					0				0	0		0		0
Provision for credit losses										0	[1]	0	[1]	(18)
Charge-offs	[2]									0	[1]	0	[1]	0
Recoveries										0		0		18
Total net charge-offs										0		0		18
Other														0
Credit loss reserves at end of period		0				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	0		0
Receivables held for investment:
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 held for investment															$ 0		$ 0

[1] The provision for credit losses and charge-offs for real estate secured receivables during the year ended December 31, 2016 includes $576 million related to the initial lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale. For the year ended December 31, 2015, the provision for credit losses and charge-offs included $234 million related to the initial lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale. See Note 7, "Receivables Held for Sale," for additional information. During the year ended December 31, 2016, net charge-offs dollars were impacted by an out of period adjustment which decreased net charge-offs by $12 million in order to properly reflect charge-offs for receivables which received a partial forgiveness of principal as a result of an account modification in prior periods. The provision for credit losses for real estate secured receivables during the year ended December 31, 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 years ended December 31, 2016, 2015 and 2014 and, accordingly, we recognized the existing credit loss reserves on these receivables as additional charge-off totaling $268 million, $1,622 million and $58 million during the years ended December 31, 2016, 2015 and 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 held for investment that are carried at the lower of amortized cost or fair value of the collateral less cost to sell which totaled $250 million and $517 million at December 31, 2015 and 2014, respectively. The reserve component above excludes credit loss reserves totaling $10 million and $25 million at December 31, 2015 and 2014, respectively, for TDR Loans held for investment 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.

[4] Includes $1,654 million of closed-end real estate secured receivables which serve as collateral for secured financings previously issued under public trusts with an outstanding balance of $879 million at December 31, 2015. See Note 17, "Variable Interest Entities," for additional information.

[5] Includes deferred origination fees, net of costs, totaling $71 million and net unamortized premium on our receivables totaling $35 million.