Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Trade accounts receivable, allowances (in dollars)	$ 1,783	$ 845
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, Authorized shares	20,000,000	20,000,000
Preferred stock, issued shares	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, Authorized shares	80,000,000	80,000,000
Common stock, issued shares	47,223,027	46,441,428
Treasury stock, shares	79,275	16,151