Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance on accounts receivable	$ 2,355	$ 1,882
Accumulated depreciation	$ 41,707	$ 39,885
Preferred stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	59,109,286	58,810,637
Common stock, shares outstanding (in shares)	59,109,286	58,810,637
Treasury stock, shares (in shares)	20,220,227	20,220,227