CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 4,092	$ 4,651
Preferred stock par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock shares authorized (in shares)	10,000,000	10,000,000
Preferred stock shares issued (in shares)	0	0
Preferred stock shares outstanding (in shares)	0	0
Common stock par value (in dollars per share)	$ 0.001	$ 0.001
Common stock shares authorized (in shares)	190,000,000	190,000,000
Common stock shares issued (in shares)	42,893,982	42,865,407
Common stock shares outstanding (in shares)	0	0