Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Property and equipment, accumulated depreciation	$ 19,817	$ 18,022
Intangible assets, accumulated amortization	$ 4,659	$ 4,145
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	3,333,333	3,333,333
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	99,000,000	99,000,000
Common stock, issued	65,493,293	64,791,670
Common stock, outstanding	65,493,293	64,791,670