Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (21,505)	$ (8,059)	$ (18,742)	$ 35,679
Other comprehensive income (loss)
Foreign currency translation adjustments	20,116	9,362	19,633	(25,962)
Derivative adjustments
Fair valuation of derivatives	(1,870)	(1,594)	(1,937)	909
Reclassification adjustment for gain on derivatives included in net income (loss)	(2,035)	(808)	(4,641)	(1,305)
Net current-period other comprehensive income (loss)	16,211	6,960	13,055	(26,358)
Total comprehensive income (loss)	$ (5,294)	$ (1,099)	$ (5,687)	$ 9,321