Property and Equipment, net - Depreciation and Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 6,821	$ 6,028	$ 13,378	$ 11,902
Depreciation and Amortization
Property, Plant and Equipment [Line Items]
Effect of the foreign exchange gains upon settlement of cash flow hedges	$ 42	$ 102	$ 193	$ 156