Secured Debt Agreements - Schedule of Secured Debt Agreements (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	$ 6,585,654	$ 2,365,336
Revolving Repurchase Facilities [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	2,780,205	2,040,783
GE Portfolio Acquisition Facility [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	3,570,131
Asset-Specific Repurchase Agreements [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	$ 235,318	$ 324,553

Carrying value, as of the balance sheet date, of securities sold under agreements to repurchase where the transferor maintains effective control over the assets, accounting for them as secured debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(m)(1)(i))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 10

-Section 55

-Paragraph 51

-URI http://asc.fasb.org/extlink&oid=51816387&loc=d3e101761-111710

Name:	us-gaap_SecuredDebtRepurchaseAgreements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant