Condensed consolidated balance sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Accounts receivable, allowance for bad debts	$ 673	$ 629
Property and equipment, accumulated depreciation	$ 28,435	$ 23,525
Class A Common Stock [Member]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	49,914,000	36,598,000
Common stock, shares outstanding	49,914,000	36,598,000
Class B Common Stock [Member]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	48,665,000	62,112,000
Common stock, shares outstanding	48,665,000	62,112,000