Secured Debt Agreements - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2015 USD ($) Facility Assets	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Proceeds from line of credit		$ 256,000,000
Secured debt agreements borrowings outstanding	$ 7,088,738,000	7,088,738,000	$ 2,365,336,000
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		1.40%
Covenants, indebtedness to total assets	83.33%	83.33%
Minimum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges		1.00%
Covenants, minimum cash liquidity amount	$ 10,000,000	$ 10,000,000
Asset-Specific Repurchase Agreements [Member]
Debt Instrument [Line Items]
Proceeds from line of credit		103,100,000
Weighted-average outstanding balance		$ 375,500,000
Closing of asset specific repurchase facilities | Assets		1
Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
Number of revolving repurchase facilities closed | Facility		3
Proceeds from line of credit		$ 762,500,000
Aggregate borrowings	2,600,000,000	$ 2,600,000,000
Weighted-average initial maturity		1 year 8 months 12 days
Weighted-average outstanding balance		$ 2,200,000,000
Approximate credit line amount	3,049,212,000	3,049,212,000
Amount available for potential future fundings of loan	412,390,000	412,390,000
Secured debt agreements borrowings outstanding	2,636,822,000	2,636,822,000	$ 2,040,783,000
Current borrowing capacity	2,636,822,000	$ 2,636,822,000
Revolving Repurchase Facilities [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation, description		L+1.80 %
LIBOR basis spread on debt obligation		1.80%
Approximate credit line amount	689,679,000	$ 689,679,000
Amount available for potential future fundings of loan	139,821,000	$ 139,821,000
Borrowings maturity term		Term matched
Current borrowing capacity	549,858,000	$ 549,858,000
GE Portfolio Acquisition Facility [Member]
Debt Instrument [Line Items]
Approximate credit line, advanced upon closing amount	4,000,000,000	4,000,000,000
Amount available for potential future fundings of loan	162,000,000	162,000,000
Secured debt agreements borrowings outstanding	4,038,165,000	4,038,165,000
GE Portfolio Acquisition Facility [Member] | Sequential Repay Advance [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	236,700,000	236,700,000
Current borrowing capacity	$ 237,200,000	$ 237,200,000
Percentage of additional advance	5.00%	5.00%
Term of maturity date	1 year
Sequential Repay Advance, percentage of guarantee rate	100.00%	100.00%
GE Portfolio Acquisition Facility [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
Approximate credit line amount	$ 4,200,000,000	$ 4,200,000,000
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.
Secured debt agreements borrowings outstanding	$ 3,800,000,000	$ 3,800,000,000
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
Weighted-Average Cash Coupon [Member] | Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation, description		LIBOR plus 1.83% per annum
LIBOR basis spread on debt obligation		1.83%
Weighted-Average All-in Cost of Credit [Member] | Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation, description		LIBOR plus 2.05% per annum
LIBOR basis spread on debt obligation		2.05%
Base Rate [Member] | GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Primary [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation, description		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	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	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	1.85%
LIBOR [Member] | GE Portfolio Acquisition Facility [Member] | Sequential Repay Advance [Member]
Debt Instrument [Line Items]
LIBOR basis spread on debt obligation, description		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	3.10%