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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		$ 272	$ 2,110	$ 311	$ 2,217
Provision for credit losses	[1]	12	192	49	219
Charge-offs	[1],[2]	(32)	(1,898)	(111)	(2,045)
Recoveries		2	4	5	17
Total net charge-offs		(30)	(1,894)	(106)	(2,028)
Credit loss reserves at end of period		254	408	254	408
Reserve components:
Collectively evaluated for impairment						$ 62		$ 107
Individually evaluated for impairment	[3]					182		288
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						10		13
Total credit loss reserves		272	2,110	311	2,217	254	$ 311	408
Receivables:
Collectively evaluated for impairment						6,783		8,481
Individually evaluated for impairment	[3]					1,109		1,485
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						268		341
Total receivables						8,160	9,156	10,307
First lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		109	1,839	137	1,898
Provision for credit losses	[1]	9	167	32	204
Charge-offs	[1],[2]	(16)	(1,808)	(69)	(1,916)
Recoveries		0	2	2	14
Total net charge-offs		(16)	(1,806)	(67)	(1,902)
Credit loss reserves at end of period		102	200	102	200
Reserve components:
Collectively evaluated for impairment						35		58
Individually evaluated for impairment	[3]					57		129
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						10		13
Total credit loss reserves		109	1,839	137	1,898	102	137	200
Receivables:
Collectively evaluated for impairment						5,735		7,114
Individually evaluated for impairment	[3]					511		806
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						240		315
Total receivables						6,486	7,302	8,235
Second lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		163	271	174	319
Provision for credit losses	[1]	3	25	17	15
Charge-offs	[1],[2]	(16)	(90)	(42)	(129)
Recoveries		2	2	3	3
Total net charge-offs		(14)	(88)	(39)	(126)
Credit loss reserves at end of period		152	208	152	208
Reserve components:
Collectively evaluated for impairment						27		49
Individually evaluated for impairment	[3]					125		159
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						0		0
Total credit loss reserves		$ 163	$ 271	$ 174	$ 319	152	174	208
Receivables:
Collectively evaluated for impairment						1,048		1,367
Individually evaluated for impairment	[3]					598		679
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						28		26
Total receivables						$ 1,674	$ 1,854	$ 2,072

[1] The provision for credit losses and charge-offs for real estate secured receivables during the three and six months ended June 30, 2016 include $6 million and $19 million, respectively, related to the lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale. For the three and six months ended June 30, 2015, the provision for credit losses and charge-offs included $220 million and $220 million, respectively, related to the lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale. See Note 4, "Receivables Held for Sale," for additional information. During the three and six months ended June 30, 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 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, 2016 and 2015 and, accordingly, we recognized the existing credit loss reserves on these receivables as additional charge-off totaling $4 million and $24 million during the three and six months ended June 30, 2016, compared with $1,578 million and $1,593 million during the three and six months ended June 30, 2015, 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 $213 million and $256 million at June 30, 2016 and 2015, respectively. The reserve component above excludes credit loss reserves totaling $9 million and $10 million at June 30, 2016 and 2015, 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.