Loans Receivable - Activity Relating to Loans Receivable Portfolio (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	$ 9,077,007
Unrealized gain on foreign currency translation	5,979	$ (20,069)
Amortization of fees and other items	8,954	$ 5,717
Ending Balance	9,313,763
Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	9,077,007
Loan originations and fundings	586,066
Loan repayments	(375,374)
Unrealized gain on foreign currency translation	27,534
Deferred fees and other items	(10,424)
Amortization of fees and other items	8,954
Ending Balance	9,313,763
Deferred Fees/Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	(31,354)
Unrealized gain on foreign currency translation	340
Deferred fees and other items	(10,424)
Amortization of fees and other items	8,954
Ending Balance	(32,484)
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	9,108,361
Beginning Balance	9,077,007
Loan originations and fundings	586,066
Loan repayments	(375,374)
Unrealized gain on foreign currency translation	27,194
Ending Balance	9,346,247
Ending Balance	$ 9,313,763