Derivative Financial Instruments - Summary of Effect of Derivative Financial Instruments on Consolidated Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Interest and related expenses	$ 234,870	$ 184,270	$ 152,416
Amount of Loss Reclassified from Accumulated OCI into Income	831	798	4
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	14,200
Net cash settlements received		26,800	18,800
Interest Rate Swaps/Derivatives [Member] | Cash Flow Hedges [Member] | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Loss Reclassified from Accumulated OCI into Income	$ 831	$ 798	$ 4