Loans Receivable - Activity Relating to Loans Receivable (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unrealized loss on foreign currency translation	$ (8,932)	$ (7,003)
Deferred origination fees and expenses		(28,015)	(9,036)
Amortization of deferred fees and expenses		(12,763)	(3,265)
Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
December 31, 2013		2,047,223
Loan fundings		2,297,545
Loan repayments and sales		(374,946)
Unrealized loss on foreign currency translation		(21,344)
Deferred origination fees and expenses		(28,015)
Amortization of deferred fees and expenses		12,763
Realized loan losses
Reclassification to other assets		(27,000)
September 30, 2014	3,906,226	3,906,226
Deferred Fees and Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
December 31, 2013		(30,004)
Unrealized loss on foreign currency translation		309
Deferred origination fees and expenses		(28,015)
Amortization of deferred fees and expenses		12,763
Realized loan losses		10,547
September 30, 2014	(34,400)	(34,400)
Principal Balance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
December 31, 2013		2,077,227
Loan fundings		2,297,545
Loan repayments and sales		(374,946)
Unrealized loss on foreign currency translation		(21,653)
Realized loan losses		10,547
Reclassification to other assets		(27,000)
September 30, 2014	$ 3,940,626	$ 3,940,626