Receivables Held for Sale - Additional Information (Detail) - USD ($)		3 Months Ended
		Mar. 31, 2017		Mar. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Lower of amortized cost or fair value adjustment on loans held for sale		$ (113,000,000)		$ 68,000,000
Aggregate unpaid balance				282,000,000
Aggregate carrying value				267,000,000
Credit loss reserve	[1],[2]			79,000,000
Initial lower of amortized cost or fair value adjustment				17,000,000
Other Revenue [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Lower of amortized cost or fair value adjustment on loans held for sale		(113,000,000)	[3]	55,000,000
Subsequent to initial transfer to held for sale				51,000,000
Initial lower of amortized cost or fair value adjustment	[4]			4,000,000
Provision for Credit Losses [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment	[5]			13,000,000
Fair Value [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Lower of amortized cost or fair value adjustment on loans held for sale		(108,000,000)		85,000,000
Fair Value [Member] | Other Revenue [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Lower of amortized cost or fair value adjustment on loans held for sale		$ (108,000,000)	[3]	72,000,000
Subsequent to initial transfer to held for sale				68,000,000
Initial lower of amortized cost or fair value adjustment	[4]			4,000,000
Fair Value [Member] | Provision for Credit Losses [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment	[5]			13,000,000
Real Estate Secured Receivable Portfolio [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Credit loss reserve				$ 20,000,000

[1] 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.

[2] 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.

[3] As all of our receivables are classified as held for sale at March 31, 2017 and December 31, 2016, for the three months ended March 31, 2017 and for all future periods, any lower of amortized cost or fair value adjustments will relate to either changes in fair value subsequent to classification as held for sale or settlements of receivables as discussed above.

[4] Represents the portion of the initial lower of amortized cost or fair value adjustment attributable to non-credit factors which are recorded as a component of total other revenues in the consolidated statement income (loss) as it reflects the impact on value caused by current marketplace conditions including changes in interest rates.

[5] 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).