Secured Debt Agreements - Additional Information (Detail)		3 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($) ExtensionOptions	Dec. 31, 2015 USD ($) Facility Assets	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Approximate credit line, outstanding amount			$ 256,000,000
Maturity date			Feb. 29, 2016
Secured debt agreements borrowings outstanding	$ 6,116,105,000		$ 6,116,105,000	$ 2,353,279,000
Covenants, minimum tangible net worth	$ 1,900,000,000		$ 1,900,000,000
Covenants, percentage of tangible assets on cash proceeds from equity issuances			75.00%
Covenants, percentage of recourse indebtedness	5.00%		5.00%
Maximum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges, in percent			1.40%
Covenants, indebtedness to total assets, in percent	83.33%		83.33%
Minimum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges, in percent			1.00%
Covenants, minimum cash liquidity amount	$ 10,000,000		$ 10,000,000
Asset-Specific Repurchase Agreements [Member]
Debt Instrument [Line Items]
Additional credit capacity			103,100,000
Weighted-average outstanding balance			$ 340,200,000	257,900,000
Closing of asset specific repurchase facilities | Assets			1
GE Portfolio Acquisition Facility [Member] | Sequential Repay Advance [Member]
Debt Instrument [Line Items]
Term of maturity date		1 year
Secured debt agreements borrowings outstanding	40,700,000		$ 40,700,000
Current borrowing capacity		$ 237,200,000
Percentage of additional advance		5.00%
Sequential Repay Advance, percentage of guarantee rate		100.00%
GE Portfolio Acquisition Facility [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
Approximate credit line amount	3,300,000,000		3,300,000,000
Approximate credit line, outstanding amount	3,200,000,000
Amount available for potential future fundings of loan	142,600,000		$ 142,600,000
GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member]
Debt Instrument [Line Items]
Weighted average rate		80.00%
Maturity date			May 20, 2020
Borrowings maturity term			The asset-specific borrowings are term matched to the underlying collateral assets with an outside maturity date of May 20, 2020, which may be extended pursuant to two one-year extension options.
Number of extension options | ExtensionOptions		2
Term of maturity date		1 year
Secured debt agreements borrowings outstanding	3,100,000,000		$ 3,100,000,000
GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percentage of guarantee rate		25.00%
Guarantee of outstanding borrowings		$ 250,000,000
Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
Number of revolving repurchase facilities closed | Facility			5
Additional credit capacity			$ 1,500,000,000
Weighted-average outstanding balance			2,500,000,000	1,400,000,000
Aggregate borrowings	2,900,000,000		$ 2,900,000,000	$ 2,000,000,000
Weighted-average advance rate			79.14%
Weighted-average initial maturity			1 year 4 months 24 days	1 year 9 months 18 days
Approximate credit line amount	4,804,267,000		$ 4,804,267,000	$ 3,377,205,000
Amount available for potential future fundings of loan	504,778,000		504,778,000	384,567,000
Current borrowing capacity	3,363,492,000		$ 3,363,492,000	2,425,350,000
Revolving Repurchase Facilities [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
Debt instrument variable rate basis			L+1.78 %
Weighted-average advance rate			79.40%
Approximate credit line amount	1,172,000,000		$ 1,172,000,000	1,000,000,000
Amount available for potential future fundings of loan	132,077,000		$ 132,077,000	101,372,000
Borrowings maturity term			Term matched
Current borrowing capacity	$ 817,562,000		$ 817,562,000	$ 585,737,000
LIBOR [Member] | GE Portfolio Acquisition Facility [Member] | Sequential Repay Advance [Member]
Debt Instrument [Line Items]
Debt instrument variable rate basis			Accrue interest at a rate equal to the sum of (i) 30-day LIBOR plus (ii) a margin of 3.10%.
LIBOR basis spread on debt obligation, in percent		3.10%
LIBOR [Member] | Revolving Repurchase Facilities [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation, in percent			1.78%
Weighted-Average Cash Coupon [Member] | Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
Debt instrument variable rate basis			LIBOR plus 1.82% per annum
LIBOR basis spread on debt obligation, in percent			1.82%	1.88%
Weighted-Average All-in Cost of Credit [Member] | Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
Debt instrument variable rate basis			LIBOR plus 2.04% per annum
LIBOR basis spread on debt obligation, in percent			2.04%	2.11%
Base Rate [Member] | GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Primary [Member]
Debt Instrument [Line Items]
Debt instrument variable rate basis			The asset-specific borrowings are currency matched to the collateral assets and accrue interest at a rate equal to the sum of (i) the applicable base rate plus (ii) a margin of 1.75%, which will increase to 1.80% and 1.85% in year four and year five, respectively.
LIBOR basis spread on debt obligation, in percent		1.75%
Base Rate [Member] | GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Primary [Member] | Year Four [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation, in percent		1.80%
Base Rate [Member] | GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Primary [Member] | Year Five [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation, in percent		1.85%