Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 4,934	$ 7,447	$ 15,755	$ 39,774
Foreign currency translation (loss) / gain	(1,296)	1,724	(2,278)	(1,382)
Other comprehensive loss	(1,296)	1,724	(2,278)	(1,382)
Comprehensive income	$ 3,638	$ 9,171	$ 13,477	$ 38,392