CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	40,000,000	40,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	1,460,000,000	1,460,000,000
Common stock, shares issued	88,593,002	88,155,707
Common stock, shares outstanding	88,593,002	88,155,707
Additional paid in capital, offering costs	$ 87,059	$ 87,059