Secured Financings - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Facility Assets
Debt Instrument [Line Items]
Number of revolving repurchase facilities closed		3
Closing of asset specific repurchase facilities		1
Proceeds from line of credit		$ 2,000,000,000
Aggregate borrowings	1,700,000,000	1,700,000,000
Weighted-average initial maturity	2 years 1 month 6 days	2 years 1 month 6 days
Covenants, minimum tangible net worth	1,100,000,000	1,100,000,000
Covenants, percentage of tangible assets on cash proceeds from equity issuances		75.00%
Covenants, percentage of recourse indebtedness	5.00%	5.00%
Weighted-Average Cash Coupon [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation	LIBOR plus 1.90% per annum	LIBOR plus 1.90% per annum
LIBOR basis spread on debt obligation	1.90%	1.90%
Weighted-Average All-in Cost of Credit [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation	LIBOR plus 2.14% per annum	LIBOR plus 2.14% per annum
LIBOR basis spread on debt obligation	2.14%	2.14%
Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
Weighted-average outstanding asset specific balance	1,600,000,000	1,200,000,000
Asset-Specific Repurchase Agreements [Member]
Debt Instrument [Line Items]
Weighted-average outstanding asset specific balance	256,900,000	251,700,000
Maximum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges		1.40
Covenants, indebtedness to total assets	83.33%	83.33%
Minimum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges		1.0
Covenants, minimum cash liquidity amount	$ 10,000,000	$ 10,000,000