Related Parties - Schedule of Shares Repurchased (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Total Purchase Price	$ 91,240	$ 63,194	$ 111,585
Stockholder/Former Director | Daniel Tierney and related entities
Related Party Transaction [Line Items]
Acquisition of beneficial ownership of securities, period		60 days
Common Class A
Related Party Transaction [Line Items]
Number of Shares Purchased	5,500	3,500
Total Purchase Price	$ 70,700	$ 41,700
Common Class A | Stockholder/ Former Director | Modified Dutch Auction Tender Offer | Stephen Schuler and related entities
Related Party Transaction [Line Items]
Number of Shares Purchased		1,708
Total Purchase Price		$ 23,918
Common Class A | Stockholder/Former Director | Modified Dutch Auction Tender Offer | Daniel Tierney and related entities
Related Party Transaction [Line Items]
Number of Shares Purchased		1,798
Total Purchase Price		$ 25,176
Common Class A | Former Stockholder | Modified Dutch Auction Tender Offer | GA-GTCO Interholdco, LLC
Related Party Transaction [Line Items]
Number of Shares Purchased		8,285
Total Purchase Price		$ 115,989
Common Class A | Former Stockholder | Modified Dutch Auction Tender Offer | Jefferies LLC
Related Party Transaction [Line Items]
Number of Shares Purchased		6,533
Total Purchase Price		$ 91,458