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, 2017	Mar. 31, 2016		Dec. 31, 2016	Mar. 31, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period			$ 311
Provision for credit losses		$ 0	37	[1]
Charge-offs	[1],[2]		(79)
Recoveries			3
Total net charge-offs			(76)
Credit loss reserves at end of period			272
Reserve components:
Collectively evaluated for impairment						$ 66
Individually evaluated for impairment	[3]					196
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						10
Total credit loss reserves			311			272
Receivables held for investment:
Collectively evaluated for impairment						7,147
Individually evaluated for impairment	[3]					1,152
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						274
Total receivables held for investment						8,573
Initial lower of amortized cost or fair value adjustment			17
Excludes Credit loss reserves for TDR Loans that are carried at the lower of amortized cost or fair value						9
Real Estate Secured Receivable Portfolio [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs			(20)
First lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period			137
Provision for credit losses	[1]		23
Charge-offs	[1],[2]		(53)
Recoveries			2
Total net charge-offs			(51)
Credit loss reserves at end of period			109
Reserve components:
Collectively evaluated for impairment						36
Individually evaluated for impairment	[3]					63
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						10
Total credit loss reserves			137			109
Receivables held for investment:
Collectively evaluated for impairment						6,028
Individually evaluated for impairment	[3]					532
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						247
Total receivables held for investment						6,807
Second lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period			174
Provision for credit losses	[1]		14
Charge-offs	[1],[2]		(26)
Recoveries			1
Total net charge-offs			(25)
Credit loss reserves at end of period			163
Reserve components:
Collectively evaluated for impairment						30
Individually evaluated for impairment	[3]					133
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						0
Total credit loss reserves			174			163
Receivables held for investment:
Collectively evaluated for impairment						1,119
Individually evaluated for impairment	[3]					620
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell						27
Total receivables held for investment						$ 1,766
Provision for Loan and Lease Losses [Member]
Receivables held for investment:
Initial lower of amortized cost or fair value adjustment	[4]		$ 13
TDR [Member]
Receivables held for investment:
Excludes TDR loans that are carried at the lower of amortized cost or fair value					$ 211

[1] The provision for credit losses and charge-offs for real estate secured receivables during the three months ended March 31, 2016 included $13 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 2, "Receivables Held for Sale," for additional information.

[2] For collateral dependent receivables that were transferred to held for sale, existing credit loss reserves at the time of transfer were 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, accordingly, we recognized the existing credit loss reserves on these receivables as additional charge-off totaling $20 million.

[3] These amounts represent TDR Loans for which we evaluated reserves using a discounted cash flow methodology. Each loan was individually identified as a TDR Loan and then grouped together with other TDR Loans with similar characteristics. The discounted cash flow impairment analysis was then applied to these groups of TDR Loans. The receivable balance above excluded TDR Loans held for investment that were carried at the lower of amortized cost or fair value of the collateral less cost to sell which totaled $211 million at March 31, 2016. The reserve component above excluded credit loss reserves totaling $9 million at March 31, 2016 for TDR Loans held for investment that were carried at the lower of amortized cost or fair value of the collateral less cost to sell.

[4] Represents the portion of the initial lower of amortized cost or fair value adjustment attributable to credit factors which are recorded as provision for credit losses in the consolidated statement of income (loss).