CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts receivable, allowance for doubtful accounts	$ 3,858	$ 4,495
Total assets of variable interest entities	148,000	152,400
Total liabilities of variable interest entities	$ 34,000	$ 35,600
Class A Common Stock
Common Stock, par value (USD per share)	$ 0.01	$ 0.01
Common Stock, shares authorized (shares)	500,000,000	500,000,000
Common Stock, shares issued (shares)	69,072,101	68,792,483
Common Stock, shares outstanding (shares)	69,072,101	68,792,483
Class B Common Stock
Common Stock, par value (USD per share)	$ 0.01	$ 0.01
Common Stock, shares authorized (shares)	140,000,000	140,000,000
Common Stock, shares issued (shares)	25,928,357	25,928,357
Common Stock, shares outstanding (shares)	25,928,357	25,928,357