CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts receivable, allowance for doubtful accounts	$ 7,343	$ 4,759
Property and equipment, accumulated depreciation	$ 30,135	$ 26,534
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	77,033,608	75,820,307
Common stock, shares outstanding	77,033,608	75,820,307
Series A Redeemable Convertible Preferred Stock [Member]
Redeemable Convertible Preferred Stock, par value	$ 0.01	$ 0.01
Redeemable Convertible Preferred Stock, shares authorized	50,000,000	50,000,000
Redeemable Convertible Preferred Stock, shares issued	14,666,667	14,666,667
Redeemable Convertible Preferred Stock, shares outstanding	14,666,667	14,666,667