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	$ 21,463	$ 32,354	$ 60,974	$ 147,197
Other comprehensive income (loss):
Foreign currency translation gain (loss)	1,705	(592)	3,305	2,263
Comprehensive income	$ 23,168	$ 31,762	$ 64,279	$ 149,460