CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounts receivable, allowance for doubtful accounts	$ 4,759	$ 4,180
Property and equipment, accumulated depreciation	$ 26,534	$ 19,822
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	100,000,000
Common stock, shares issued	75,820,307	60,242,818
Common stock, shares outstanding	75,820,307	60,242,818
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	10,000,000
Redeemable Convertible Preferred Stock, shares issued	14,666,667	0
Redeemable Convertible Preferred Stock, shares outstanding	14,666,667	0