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
		Mar. 31, 2016		Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		$ 311		$ 2,217
Provision for credit losses	[1]	37		27
Charge-offs	[2]	(79)	[1]	(147)
Recoveries		3		13
Total net charge-offs		(76)		(134)
Credit loss reserves at end of period		272		2,110
Reserve components:
Collectively evaluated for impairment					$ 66		$ 208
Individually evaluated for impairment	[3]				196		1,875
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell					10		27
Total credit loss reserves		311		2,217	272	$ 311	2,110
Receivables:
Collectively evaluated for impairment					7,147		11,398
Individually evaluated for impairment	[3]				1,152		9,802
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell					274		529
Total receivables					8,573	9,156	21,729
First lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		137		1,898
Provision for credit losses	[1]	23		37
Charge-offs	[2]	(53)	[1]	(108)
Recoveries		2		12
Total net charge-offs		(51)		(96)
Credit loss reserves at end of period		109		1,839
Reserve components:
Collectively evaluated for impairment					36		155
Individually evaluated for impairment	[3]				63		1,657
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell					10		27
Total credit loss reserves		137		1,898	109	137	1,839
Receivables:
Collectively evaluated for impairment					6,028		9,872
Individually evaluated for impairment	[3]				532		8,936
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell					247		500
Total receivables					6,807	7,302	19,308
Second lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		174		319
Provision for credit losses	[1]	14		(10)
Charge-offs	[2]	(26)	[1]	(39)
Recoveries		1		1
Total net charge-offs		(25)		(38)
Credit loss reserves at end of period		163		271
Reserve components:
Collectively evaluated for impairment					30		53
Individually evaluated for impairment	[3]				133		218
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell					0		0
Total credit loss reserves		$ 174		$ 319	163	174	271
Receivables:
Collectively evaluated for impairment					1,119		1,526
Individually evaluated for impairment	[3]				620		866
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell					27		29
Total receivables					$ 1,766	$ 1,854	$ 2,421

[1] The provision for credit losses and charge-offs for real estate secured receivables during the three months ended March 31, 2016 include $13 million related to the lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale. See Note 5, "Receivables Held for Sale," for additional information. The provision for credit losses for real estate secured receivables during the three months ended March 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 three months ended March 31, 2016 and 2015 and, accordingly, we recognized the existing credit loss reserves on these receivables as additional charge-off totaling $20 million during the three months ended March 31, 2016 compared with $15 million during the three months ended March 31, 2015.

[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 $211 million and $399 million at March 31, 2016 and 2015, respectively. The reserve component above excludes credit loss reserves totaling $9 million and $22 million at March 31, 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.