Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts		$ 4,287	$ 4,814
Preferred stock par value (usd per share)		$ 0.001	$ 0.001
Preferred stock authorized (shares)		40,000,000	40,000,000
Preferred stock issued (shares)		0	0
Preferred stock outstanding (shares)		0	0
Treasury stock (shares)		14,102,185	14,102,185
Total Assets	[1]	$ 8,059,318	$ 8,169,328
Liabilities	[1]	4,647,936	4,952,148
Variable Interest Entity, Primary Beneficiary
Total Assets		74,000	81,000
Liabilities		$ 26,000	$ 29,000
Class A Common Stock
Common stock, par value (usd per share)		$ 0.001	$ 0.001
Common stock, authorized (shares)		1,000,000,000	1,000,000,000
Common stock, issued shares (shares)		101,727,977.000	101,429,999
Common stock, outstanding (shares)		87,625,792	87,327,814
Class B Common Stock
Common stock, par value (usd per share)		$ 0.001	$ 0.001
Common stock, authorized (shares)		1,000,000,000	1,000,000,000
Common stock, issued shares (shares)		5,557	5,557
Common stock, outstanding (shares)		5,557	5,557
Senior Secured Credit Agreement | Term Loan Facility
Unamortized discounts and debt issuance costs		$ 22,000	$ 24,000
Noncurrent | Senior Secured Credit Agreement | Term Loan Facility
Unamortized discounts and debt issuance costs		$ 32,917	$ 36,332

[1] (1) The Company’s consolidated total assets as of June 30, 2018 and December 31, 2017 include total assets of variable interest entities (“VIEs”) of $74 million and $81 million, respectively, which can only be used to settle the obligations of the VIEs. The Company’s consolidated total liabilities as of June 30, 2018 and December 31, 2017 include total liabilities of the VIEs of $26 million and $29 million, respectively, for which the creditors of the VIEs have no recourse to the Company (see Note 1).