CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Accounts receivable allowances	$ 431	$ 433
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	96,048,823	89,066,031
Common stock, shares outstanding	96,048,823	89,066,031