Loans Receivable - Activity Relating to Loans Receivable Portfolio (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance			$ 9,077,007
Unrealized (loss) gain on foreign currency translation	$ (21,321)	$ 15,732	(15,343)	$ (4,336)
Amortization of fees and other items			20,360	$ 12,198
Ending Balance	9,090,934		9,090,934
Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance			9,077,007
Loan fundings			1,401,871
Loan repayments			(1,341,814)
Unrealized (loss) gain on foreign currency translation			44,877
Deferred fees and other items			(21,613)
Amortization of fees and other items			20,360
Ending Balance	9,090,934		9,090,934
Deferred Fees/Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance			(31,354)
Unrealized (loss) gain on foreign currency translation			974
Deferred fees and other items			(21,613)
Amortization of fees and other items			20,360
Ending Balance	(31,633)		(31,633)
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance			9,108,361
Loan fundings			1,401,871
Loan repayments			(1,341,814)
Unrealized (loss) gain on foreign currency translation			45,851
Ending Balance	$ 9,122,567		$ 9,122,567