Fair Value Measurements - Carrying and Estimated Fair Value (Detail) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Financial assets:
Cash		$ 120	$ 124
Securities purchased under agreements to resell		824	2,724
Financial liabilities:
Long-term debt		4,494	9,510
Level 1 [Member]
Financial assets:
Cash		120	124
Securities purchased under agreements to resell		0	0
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		0
Real estate secured receivables held for sale		0	0
Due from affiliates		0	0
Financial liabilities:
Due to affiliates carried at fair value		0	0
Due to affiliates not carried at fair value		0	0
Level 1 [Member] | First lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		0
Level 1 [Member] | Second lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		0
Level 2 [Member]
Financial assets:
Cash		0	0
Securities purchased under agreements to resell		824	2,724
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		0
Real estate secured receivables held for sale		757	0
Due from affiliates		78	128
Financial liabilities:
Due to affiliates carried at fair value		497	496
Due to affiliates not carried at fair value		4,425	5,693
Level 2 [Member] | First lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		0
Level 2 [Member] | Second lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		0
Level 3 [Member]
Financial assets:
Cash		0	0
Securities purchased under agreements to resell		0	0
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		8,330
Real estate secured receivables held for sale		9,500	8,668
Due from affiliates		0	0
Financial liabilities:
Due to affiliates carried at fair value		0	0
Due to affiliates not carried at fair value		0	0
Level 3 [Member] | First lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		7,174
Level 3 [Member] | Second lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		1,156
Carrying Value [Member]
Financial assets:
Cash		120	124
Securities purchased under agreements to resell		824	2,724
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		8,987
Real estate secured receivables held for sale		10,148	8,265
Due from affiliates		78	128
Financial liabilities:
Due to affiliates carried at fair value		497	496
Due to affiliates not carried at fair value		4,327	5,429
Carrying Value [Member] | First lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		7,237
Carrying Value [Member] | Second lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		1,750
Estimated Fair Value [Member]
Financial assets:
Cash		120	124
Securities purchased under agreements to resell		824	2,724
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		8,330
Real estate secured receivables held for sale		10,257	8,668
Due from affiliates		78	128
Financial liabilities:
Due to affiliates carried at fair value		497	496
Due to affiliates not carried at fair value		4,425	5,693
Estimated Fair Value [Member] | First lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		7,174
Estimated Fair Value [Member] | Second lien [Member]
Real estate secured receivables held for investment:
Total real estate secured receivables held for investment	[1]		1,156
Long-term Debt Carried at Fair Value [Member] | Level 1 [Member]
Financial liabilities:
Long-term debt		0	0
Long-term Debt Carried at Fair Value [Member] | Level 2 [Member]
Financial liabilities:
Long-term debt		1,431	3,257
Long-term Debt Carried at Fair Value [Member] | Level 3 [Member]
Financial liabilities:
Long-term debt		0	0
Long-term Debt Carried at Fair Value [Member] | Carrying Value [Member]
Financial liabilities:
Long-term debt		1,431	3,257
Long-term Debt Carried at Fair Value [Member] | Estimated Fair Value [Member]
Financial liabilities:
Long-term debt		1,431	3,257
Long Term Debt Not Carried at Fair Value [Member] | Level 1 [Member]
Financial liabilities:
Long-term debt		0	0
Long Term Debt Not Carried at Fair Value [Member] | Level 2 [Member]
Financial liabilities:
Long-term debt		3,469	6,664
Long Term Debt Not Carried at Fair Value [Member] | Level 3 [Member]
Financial liabilities:
Long-term debt		0	0
Long Term Debt Not Carried at Fair Value [Member] | Carrying Value [Member]
Financial liabilities:
Long-term debt		3,063	6,253
Long Term Debt Not Carried at Fair Value [Member] | Estimated Fair Value [Member]
Financial liabilities:
Long-term debt		$ 3,469	$ 6,664

[1] The receivable held for investment carrying value included in this table reflects the principal amount outstanding on the loan net of any charge-off recorded in accordance with our existing charge-off policies and includes certain basis adjustments to the loan such as unearned income, unamortized deferred fees and costs on originated loans, purchase accounting fair value adjustments and premiums or discounts on purchased loans. The receivable held for investment carrying value included in this table also includes accrued finance charges and is net of credit loss reserves. However, the basis adjustments on the loans, accrued finance charges and credit loss reserves are excluded in other presentations of dollars of two-months-and-over contractual delinquency, nonaccrual receivable and nonperforming receivables held for investment account balances.