Loans Receivable, Net - Activity Relating to Loans Receivable Portfolio (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	$ 8,692,978
Unrealized gain (loss) on foreign currency translation	7,770	$ 5,979
Amortization of fees and other items	8,808	$ 8,954
Ending Balance	8,721,768
Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	8,692,978
Loan fundings	702,353
Loan repayments	(695,758)
Unrealized gain (loss) on foreign currency translation	25,816
Deferred fees and other items	(12,429)
Amortization of fees and other items	8,808
Ending Balance	8,721,768
Deferred Fees/Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	(34,240)
Unrealized gain (loss) on foreign currency translation	(67)
Deferred fees and other items	(12,429)
Amortization of fees and other items	8,808
Ending Balance	(37,928)
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	8,727,218
Loan fundings	702,353
Loan repayments	(695,758)
Unrealized gain (loss) on foreign currency translation	25,883
Ending Balance	$ 8,759,696