Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Consolidated net income (loss)	$ (26,651)	$ 60,762	$ 25,598
Currency translation adjustment, net of tax	10,176	(3,993)	(10,436)
Comprehensive income (loss) allocated to common stockholders	$ (16,475)	$ 56,769	$ 15,162