Derivative Financial Instruments - Summary of Effect of Derivative Financial Instruments on Consolidated Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total interest and related income	$ 146,400
Interest and related expenses	67,891	$ 45,373	$ 168,917	$ 139,819
Amount of Loss Reclassified from Accumulated OCI into Income	41		(900)
Foreign Currency Contracts [Member] | Net Investment Hedges [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net cash settlements on our foreign currency forward contracts	8,700	$ 19,200	11,800	$ 17,400
Interest Rate Swaps/Derivatives [Member] | Cash Flow Hedges [Member] | Interest Income [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Loss Reclassified from Accumulated OCI into Income	$ 41		$ 900