Receivables Held for Sale - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended			6 Months Ended
		Jul. 31, 2016	Jun. 30, 2016	Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Threshold, days past due to initiate sale activities for first lien real estate secured receivables						180 days
Aggregate unpaid balance			$ 76,000,000	$ 11,000,000,000		$ 358,000,000		$ 11,431,000,000
Aggregate carrying value			75,000,000	11,504,000,000		342,000,000		11,815,000,000
Initial lower of amortized cost or fair value adjustment			8,000,000			25,000,000		220,000,000
Gain on sale of real estate secured receivables			423,000,000	18,000,000		423,000,000		18,000,000
Provision for Credit Losses [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment	[1]		6,000,000	220,000,000		19,000,000		220,000,000
Other Revenue [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment			2,000,000	0	[2]	6,000,000	[2]	0	[2]
Subsequent to initial transfer to held for sale			54,000,000	54,000,000		105,000,000		71,000,000
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	[1]		6,000,000	220,000,000		19,000,000		220,000,000
Fair Value [Member] | Other Revenue [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment			2,000,000	0	[2]	6,000,000	[2]	0	[2]
Subsequent to initial transfer to held for sale			62,000,000	53,000,000		130,000,000		53,000,000
First and Second Mortgage [Member] | Fair Value [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment			6,000,000	$ 220,000,000		$ 19,000,000		$ 220,000,000
Real Estate Secured Receivables Held for Sale [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Aggregate unpaid balance prior to sale			4,722,000,000
Aggregate carrying value prior to sale			4,219,000,000
Aggregate cash consideration received			4,667,000,000
Gain on sale of real estate secured receivables			$ 423,000,000
Real Estate Secured Receivables Held for Sale [Member] | Subsequent Event [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Aggregate unpaid balance prior to sale		$ 930,000,000
Aggregate carrying value prior to sale		707,000,000
Aggregate cash consideration received		716,000,000
Scenario, Forecast [Member] | Real Estate Secured Receivables Held for Sale [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gain on sale of real estate secured receivables		$ (5,000,000)

[1] Represents the portion of the initial lower of amortized cost or fair value adjustment attributable to credit factors which was recorded as provision for credit losses in the consolidated statement of income (loss) as there was no objective, verifiable evidence to indicate non-credit factors were associated with the decline in fair value.

[2] Represents the portion of the initial lower of amortized cost or fair value adjustment attributable to non-credit factors which was 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.