Loans Receivable - Overall Statistics for Loans Receivable Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2014 SecurityLoan	Dec. 31, 2013 SecurityLoan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	$ 3,906,226	$ 2,047,223
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans	55	31
Principal Balance	3,940,626	2,077,227
Net book value	3,906,226	2,047,223
Unfunded commitments	$ 513,363	$ 164,283
Weighted-average cash coupon	L+4.42 %	L+4.64 %
Weighted-average all-in yield	L+4.97 %	L+5.26 %
Weighted-average maximum maturity (years)	3 years 10 months 24 days	4 years 1 month 6 days

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant