CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Accounts receivable allowance	$ 3,039	$ 1,186
Prepaid and other assets allowance	50	45
Employee loans current allowance	23	0
Assets, Noncurrent [Abstract]
Employee loans long-term allowance	0	0
Other long-term assets allowance	$ 0	$ 140
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	160,000,000	160,000,000
Common stock, shares issued (in shares)	54,011,579	53,003,420
Common stock, shares outstanding (in shares)	53,991,844	52,983,685