Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018
Accounting Policies [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 12,858	$ 9,247	$ 7,820
Net foreign currency gains (losses)	(13,315)	$ 7,955	$ 7,820
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Leases, Future Minimum Payments Due	259,895
Leases Accounting Standards Update
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Leases, Future Minimum Payments Due	$ 259,895
Maximum | Subsequent Event | Revenue Accounting Standards Update
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				$ 35,000