Secured Debt Agreements - Additional Information (Detail)				3 Months Ended		6 Months Ended			12 Months Ended
	Jul. 25, 2016	Jul. 24, 2016	Jun. 30, 2016 USD ($) ExtensionOptions	Jun. 30, 2016 USD ($) ExtensionOptions	Jun. 30, 2015 USD ($) ExtensionOptions	Jun. 30, 2016 USD ($) ExtensionOptions Facility	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($) ExtensionOptions	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Maturity date						Aug. 31, 2016
Term of maturity date						6 months
Secured debt agreements borrowings outstanding			$ 6,198,093,000	$ 6,198,093,000		$ 6,198,093,000	$ 6,116,105,000		$ 6,116,105,000
Interest expense				49,065,000	$ 30,634,000	94,446,000		$ 54,796,000
Covenants, minimum tangible net worth			$ 1,900,000,000	$ 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%		5.00%
Maximum [Member]
Debt Instrument [Line Items]
Covenants, indebtedness to total assets, in percent			83.33%	83.33%		83.33%
Minimum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges, in percent						140.00%
Covenants, minimum cash liquidity amount			$ 10,000,000	$ 10,000,000		$ 10,000,000
Asset-Specific Financings [Member]
Debt Instrument [Line Items]
Weighted-average outstanding balance						$ 540,100,000	648,900,000
Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
Number of revolving repurchase facilities closed | Facility						2
Additional credit capacity						$ 1,300,000,000
Weighted-average outstanding balance						2,900,000,000	2,400,000,000
Aggregate borrowings			3,100,000,000	3,100,000,000		$ 3,100,000,000	2,500,000,000		$ 2,500,000,000
Weighted-average advance rate						79.10%			78.80%
Weighted-average initial maturity						1 year 3 months 18 days			1 year 3 months 18 days
Maximum Facility Size			5,530,725,000	5,530,725,000		$ 5,530,725,000	4,332,267,000		$ 4,332,267,000
Amount available for potential future fundings of loan			369,004,000	369,004,000		369,004,000	487,028,000		487,028,000
Current borrowing capacity			3,511,408,000	3,511,408,000		$ 3,511,408,000	2,982,833,000		2,982,833,000
Revolving Repurchase Facilities [Member] | Bank of America [Member]
Debt Instrument [Line Items]
Weighted-average advance rate						79.30%
Maximum Facility Size			$ 750,000,000	$ 750,000,000		$ 750,000,000	750,000,000		750,000,000
Number of extension options | ExtensionOptions			2	2		2
Term of maturity date						1 year
Amount available for potential future fundings of loan			$ 14,345,000	$ 14,345,000		$ 14,345,000	46,917,000		46,917,000
Borrowings maturity term						May 21, 2021
Current borrowing capacity			512,679,000	512,679,000		$ 512,679,000	665,861,000		665,861,000
Revolving Repurchase Facilities [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
Weighted-average advance rate						79.50%
Maximum Facility Size			2,000,000,000	2,000,000,000		$ 2,000,000,000	1,000,000,000		1,000,000,000
Amount available for potential future fundings of loan			273,568,000	273,568,000		$ 273,568,000	124,818,000		124,818,000
Borrowings maturity term						Term matched
Current borrowing capacity			1,099,823,000	1,099,823,000		$ 1,099,823,000	687,200,000		687,200,000
Revolving Repurchase Facilities [Member] | JP Morgan [Member]
Debt Instrument [Line Items]
Weighted-average advance rate						78.80%
Maximum Facility Size			500,000,000	500,000,000		$ 500,000,000	524,547,000		524,547,000
Amount available for potential future fundings of loan			10,293,000	10,293,000		$ 10,293,000	82,681,000		82,681,000
Borrowings maturity term						January 7, 2018
Current borrowing capacity			404,031,000	404,031,000		$ 404,031,000	464,723,000		464,723,000
Revolving Repurchase Facilities [Member] | JP Morgan [Member] | Subsequent Events [Member]
Debt Instrument [Line Items]
Maturity date	Jan. 07, 2019	Jan. 07, 2018
Revolving Repurchase Facilities [Member] | Extended Maturity [Member] | Bank of America [Member]
Debt Instrument [Line Items]
Maximum Facility Size			$ 750,000,000	$ 750,000,000		$ 750,000,000
Maturity date						May 21, 2021
Number of extension options | ExtensionOptions			2	2		2
Term of maturity date						1 year
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			$ 237,200,000
Percentage of additional advance					5.00%			5.00%
Sequential Repay Advance, percentage of guarantee rate					100.00%			100.00%
GE Portfolio Acquisition Facility [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
Additional credit capacity				$ 125,000,000
Maximum Facility Size			$ 2,800,000,000	2,800,000,000		$ 2,800,000,000
Approximate credit line, outstanding amount			2,600,000,000
Amount available for potential future fundings of loan			238,700,000	238,700,000		$ 238,700,000
GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member]
Debt Instrument [Line Items]
Maturity date						May 20, 2020
Number of extension options | ExtensionOptions					2			2
Term of maturity date					1 year
Weighted average rate					80.00%
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.
Secured debt agreements borrowings outstanding			2,600,000,000	2,600,000,000		$ 2,600,000,000	$ 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%			25.00%
Guarantee of outstanding borrowings					$ 250,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Weighted-average outstanding balance						35,200,000
Interest expense						494,000,000
Amortization of deferred fees and expenses						121,000,000
Revolving Credit Facility [Member] | Barclays [Member]
Debt Instrument [Line Items]
Maximum Facility Size			$ 125,000,000	$ 125,000,000		$ 125,000,000
Number of extension options | ExtensionOptions			2	2		2
Term of maturity date						1 year
First mortgage bridge to term financing maximum period						6 months
Base Rate [Member] | GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Primary [Member]
Debt Instrument [Line Items]
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]
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]
Basis spread on debt obligation, in percent					1.85%
LIBOR [Member] | Revolving Repurchase Facilities [Member] | Bank of America [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent						1.68%
LIBOR [Member] | Revolving Repurchase Facilities [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent						1.82%
LIBOR [Member] | Revolving Repurchase Facilities [Member] | JP Morgan [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent						1.86%
LIBOR [Member] | Revolving Repurchase Facilities [Member] | Weighted-Average Cash Coupon [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent						1.85%			1.83%
LIBOR [Member] | Revolving Repurchase Facilities [Member] | Weighted-Average All-in Cost of Credit [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent						2.04%			2.05%
LIBOR [Member] | GE Portfolio Acquisition Facility [Member] | Sequential Repay Advance [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent					3.10%
LIBOR basis spread on debt obligation						30-day LIBOR