Receivables Held for Sale - Summary of Activity in Receivables Held for Sale (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Receivables Held for Sale, Activity [Roll Forward]
Real estate secured receivables held for sale at beginning of period	[1]			$ 5,674
Real estate secured receivables held for sale at end of period	[1]	$ 256		256
Receivables Held for Sale, Initial Lower of Amortized Cost or Fair Value Adjustment			$ (562)		$ (587)
Mortgage Loans on Real Estate [Member]
Receivables Held for Sale, Activity [Roll Forward]
Real estate secured receivables held for sale at beginning of period		1,346	3,796	5,674	8,265
Transfer of real estate secured receivables into held for sale at the lower of amortized cost or fair value	[2],[3]	0	7,281	0	7,574
Real estate secured receivable sales		(1,048)	(714)	(5,267)	(4,933)
Lower of amortized cost or fair value adjustment on real estate secured receivables held for sale subsequent to initial transfer to held for sale		(16)	(3)	155	(108)
Carrying value of real estate secured receivables held for sale transferred to real estate owned (REO)		(2)	(11)	(19)	(45)
Carrying value of real estate secured receivables held for sale settled through short sale		(2)	(8)	(17)	(26)
Change in real estate secured receivable balance, including collections		(22)	(193)	(270)	(579)
Real estate secured receivables held for sale at end of period	[4]	$ 256	$ 10,148	$ 256	$ 10,148

[1] At September 30, 2017 and December 31, 2016, contractually delinquent real estate secured receivables held for sale includes $14 million and $235 million, respectively, that are in the process of foreclosure.

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

[3] During the three and nine months ended September 30, 2016, the initial lower of amortized cost or fair value adjustment recorded on receivables transferred into held for sale totaled $562 million and $587 million, respectively.

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