Receivables Held for Sale - Summary of Activity in Receivables Held for Sale (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Receivables Held for Sale, Activity [Roll Forward]
Real estate secured receivables held for sale at beginning of period	[1],[2]			$ 5,674
Real estate secured receivables held for sale at end of period	[1],[2]	$ 1,346		1,346
Receivables Held for Sale, Initial Lower of Amortized Cost or Fair Value Adjustment			$ (8)		$ (25)
Mortgage Loans on Real Estate [Member]
Receivables Held for Sale, Activity [Roll Forward]
Real estate secured receivables held for sale at beginning of period		1,911	8,185	5,674	8,265
Transfer of real estate secured receivables into held for sale at the lower of amortized cost or fair value	[3],[4]	0	63	0	293
Real estate secured receivable sales		(554)	(4,219)	(4,219)	(4,219)
Lower of amortized cost or fair value adjustment on real estate secured receivables held for sale subsequent to initial transfer to held for sale		58	(54)	171	(105)
Carrying value of real estate secured receivables held for sale transferred to real estate owned (REO)		(6)	(20)	(17)	(34)
Carrying value of real estate secured receivables held for sale settled through short sale		(7)	(10)	(15)	(18)
Change in real estate secured receivable balance, including collections		(56)	(149)	(248)	(386)
Real estate secured receivables held for sale at end of period	[5]	$ 1,346	$ 3,796	$ 1,346	$ 3,796

[1] At June 30, 2017 and December 31, 2016, receivables held for sale includes $428 million and $750 million, respectively, of closed-end real estate secured receivables which are part of a collateralized funding transaction. These receivables will be sold when they are contractually released as collateral under the public trust and become available for sale. See Note 10, "Variable Interest Entities," for further discussion of our collateralized funding transactions.

[2] At June 30, 2017 and December 31, 2016, contractually delinquent real estate secured receivables held for sale includes $172 million and $235 million, respectively, that are in the process of foreclosure.

[3] Amount includes any accrued interest associated with the receivable.

[4] During the three and six months ended June 30, 2016, the initial lower of amortized cost or fair value adjustment recorded on receivables transferred into held for sale totaled $8 million and $25 million, respectively.

[5] Real estate secured receivables held for sale in the table above are presented net of the valuation allowance.