Fair Value Measurements - Assets and Liabilities Recorded at Fair Value on Non-recurring Basis (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Gains (Losses)		$ (99)	$ (93)
Real Estate Secured Receivables Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Gains (Losses)		(68)	(17)
Receivables Held-for-Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Gains (Losses)	[1]	(26)	(72)
Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Gains (Losses)	[2]	(5)	(4)
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		0		$ 0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		1,475		0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		7,235		8,668
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
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
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
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
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		1,653	1,048
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		1,299	333
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]	274	529
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]	80	186
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		6,886	764
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		6,886	764	8,265
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
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
Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total receivables held for sale		8,710		$ 8,668
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		8,539	1,812
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		8,185	1,097
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]	274	529
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]	80	186
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		$ 1,299	$ 333

[1] Total gains (losses) for the three months ended March 31, 2016 and 2015 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.