Receivables Held for Sale - Summary of Components of Cumulative Lower of Amortized Cost or Fair Value Adjustment (Detail) - USD ($)		1 Months Ended	12 Months Ended
		Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Lower of amortized cost or fair value adjustment recorded as a component of:
Initial lower of amortized cost or fair value adjustment		$ 541,000,000	$ 587,000,000	$ 234,000,000
Lower of amortized cost or fair value adjustment on loans held for sale			788,000,000	364,000,000	$ (201,000,000)
Fair Value [Member]
Lower of amortized cost or fair value adjustment recorded as a component of:
Lower of amortized cost or fair value adjustment on loans held for sale			850,000,000	389,000,000	(344,000,000)
Settlement (Including Short Sales) [Member]
Lower of amortized cost or fair value adjustment recorded as a component of:
Lower of amortized cost or fair value adjustment on loans held for sale	[1]		(62,000,000)	(25,000,000)	143,000,000
Provision for Credit Losses [Member]
Lower of amortized cost or fair value adjustment recorded as a component of:
Initial lower of amortized cost or fair value adjustment	[2]		576,000,000	234,000,000	0
Provision for Credit Losses [Member] | Fair Value [Member]
Lower of amortized cost or fair value adjustment recorded as a component of:
Initial lower of amortized cost or fair value adjustment	[2]		576,000,000	234,000,000	0
Provision for Credit Losses [Member] | Settlement (Including Short Sales) [Member]
Lower of amortized cost or fair value adjustment recorded as a component of:
Initial lower of amortized cost or fair value adjustment	[1],[2]		0	0	0
Other Revenue [Member]
Lower of amortized cost or fair value adjustment recorded as a component of:
Initial lower of amortized cost or fair value adjustment	[3]		11,000,000	0	113,000,000
Subsequent to initial transfer to held for sale			201,000,000	130,000,000	(314,000,000)
Lower of amortized cost or fair value adjustment on loans held for sale			212,000,000	130,000,000	(201,000,000)
Other Revenue [Member] | Fair Value [Member]
Lower of amortized cost or fair value adjustment recorded as a component of:
Initial lower of amortized cost or fair value adjustment	[3]		11,000,000	0	113,000,000
Subsequent to initial transfer to held for sale			263,000,000	155,000,000	(457,000,000)
Lower of amortized cost or fair value adjustment on loans held for sale			274,000,000	155,000,000	(344,000,000)
Other Revenue [Member] | Settlement (Including Short Sales) [Member]
Lower of amortized cost or fair value adjustment recorded as a component of:
Initial lower of amortized cost or fair value adjustment	[1],[3]		0	0	0
Subsequent to initial transfer to held for sale	[1]		(62,000,000)	(25,000,000)	143,000,000
Lower of amortized cost or fair value adjustment on loans held for sale	[1]		$ (62,000,000)	$ (25,000,000)	$ 143,000,000

[1] Reflects receivable settlements due to either receivable payoffs (including short sales) or transfers of receivables to REO and reflects either a reversal of the non-credit fair value adjustment previously recorded on these receivables or an additional lower of amortized cost or fair value adjustment required at the time of settlement.

[2] 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).

[3] 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.