Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss) allocated to common stockholders	$ (5,912)	$ 13,110	$ (413)	$ 37,095
Currency translation adjustment, net of tax	2,541	805	9,271	1,765
Comprehensive income (loss) allocated to common stockholders	$ (3,371)	$ 13,915	$ 8,858	$ 38,860