Fair Value Measurements - Assets and Liabilities Recorded at Fair Value on Non-recurring Basis (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Gains (Losses)		$ (122)	$ (13)	$ (329)	$ (70)
Real Estate Secured Receivables Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Gains (Losses)		(83)	84	(154)	292
Receivables Held-for-Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Gains (Losses)	[1]	(32)	(86)	(159)	(319)
Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Gains (Losses)	[2]	(7)	(11)	(16)	(43)
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		0		0		$ 0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		1,635		1,635		0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		8,752		8,752		937
Non-Recurring Fair Value Measurements [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis		0	0	0	0
Non-Recurring Fair Value Measurements [Member] | Level 1 [Member] | Real Estate Secured Receivables Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		0	0	0	0
Non-Recurring Fair Value Measurements [Member] | Level 1 [Member] | Receivables Held-for-Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Receivables held for investment	[1]	0	0	0	0
Non-Recurring Fair Value Measurements [Member] | Level 1 [Member] | Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate owned	[2]	0	0	0	0
Non-Recurring Fair Value Measurements [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis		2,089	1,866	2,089	1,866
Non-Recurring Fair Value Measurements [Member] | Level 2 [Member] | Real Estate Secured Receivables Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		1,635	998	1,635	998
Non-Recurring Fair Value Measurements [Member] | Level 2 [Member] | Receivables Held-for-Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Receivables held for investment	[1]	328	690	328	690
Non-Recurring Fair Value Measurements [Member] | Level 2 [Member] | Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate owned	[2]	126	178	126	178
Non-Recurring Fair Value Measurements [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis		8,406	842	8,406	842
Non-Recurring Fair Value Measurements [Member] | Level 3 [Member] | Real Estate Secured Receivables Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		8,406	842	8,406	842	860
Non-Recurring Fair Value Measurements [Member] | Level 3 [Member] | Receivables Held-for-Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Receivables held for investment	[1]	0	0	0	0
Non-Recurring Fair Value Measurements [Member] | Level 3 [Member] | Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate owned	[2]	0	0	0	0
Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		10,387		10,387		$ 937
Total [Member] | Non-Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis		10,495	2,708	10,495	2,708
Total [Member] | Non-Recurring Fair Value Measurements [Member] | Real Estate Secured Receivables Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		10,041	1,840	10,041	1,840
Total [Member] | Non-Recurring Fair Value Measurements [Member] | Receivables Held-for-Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Receivables held for investment	[1]	328	690	328	690
Total [Member] | Non-Recurring Fair Value Measurements [Member] | Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate owned	[2]	126	178	126	178
Real Estate Secured Receivables Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets transferred from Level 3 to Level 2		$ 1,635	$ 998	$ 2,077	$ 2,172

[1] Total gains (losses) for the three and nine months ended September 30, 2015 and 2014 include amounts recorded on receivables that were subsequently transferred to held for sale.

[2] Real estate owned is required to be reported on the balance sheet net of transactions costs. The real estate owned amounts in the table above reflect the fair value of the underlying asset unadjusted for transaction costs.