Secured Financings - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014 Participants Facility Assets
Debt Instrument [Line Items]
Number of revolving repurchase facilities closed	3
Closing of asset specific repurchase facilities	2
Number of senior loan participations sold	3
Proceeds from line of credit	$ 2,200,000,000
Aggregate borrowings	2,000,000,000
Weighted-average initial maturity	1 year 9 months 18 days
Covenants, minimum tangible net worth	1,100,000,000
Covenants, percentage of tangible assets on cash proceeds from equity issuances	75.00%
Covenants, percentage of recourse indebtedness	5.00%
Maximum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges	1.40
Covenants, indebtedness to total assets	83.33%
Minimum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges	1.0
Covenants, minimum cash liquidity amount	10,000,000
Asset-Specific Repurchase Agreements [Member]
Debt Instrument [Line Items]
Weighted-average outstanding asset specific balance	257,900,000
Weighted-Average Cash Coupon [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation	LIBOR plus 1.88% per annum
LIBOR basis spread on debt obligation	1.88%
Weighted-Average All-in Cost of Credit [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation	LIBOR plus 2.11% per annum
LIBOR basis spread on debt obligation	2.11%
Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
Weighted-average outstanding asset specific balance	$ 1,400,000,000