CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property and equipment, accumulated depreciation	$ 103,866	$ 100,851
Intangible assets, accumulated amortization	$ 50,640	$ 49,080
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares, issued (in shares)	128,567,504	128,391,456
Common stock, shares, outstanding (in shares)	128,160,291	128,077,651
Treasury stock, at cost (in shares)	407,213	313,805
Series A Preferred Stock
Convertible preferred stock series, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock series, shares authorized (in shares)	825,000	825,000
Convertible preferred stock series, shares issued (in shares)	21,630	21,630
Convertible preferred stock series, shares outstanding (in shares)	21,630	21,630
Convertible preferred stock series, liquidation preference	$ 3,356	$ 3,264
Series C Preferred Stock
Convertible preferred stock series, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock series, shares authorized (in shares)	625,000	625,000
Convertible preferred stock series, shares issued (in shares)	614,177	614,177
Convertible preferred stock series, shares outstanding (in shares)	614,177	614,177
Convertible preferred stock series, liquidation preference	$ 97,391	$ 94,706