CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common stock, par value per share (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	43,389,576	42,291,352
Common stock, shares outstanding	43,373,611	42,282,741
Treasury stock, at cost, outstanding	15,965	8,611