Related Parties - Schedule of Shares Repurchased (Details) - 6 months ended Jun. 30, 2015 - USD ($) shares in Thousands, $ in Thousands	Total
Related Party Transaction [Line Items]
Total Purchase Price	$ 10,653
Director/Stockholder [Member] \| Daniel Tierney [Member]
Related Party Transaction [Line Items]
Acquisition of beneficial ownership of securities, period	60 days
Tender Offer [Member] \| Common Class A [Member] \| Director/Stockholder [Member] \| Stephen Schuler [Member]
Related Party Transaction [Line Items]
Number of Shares Purchased	1,708
Total Purchase Price	$ 23,918
Tender Offer [Member] \| Common Class A [Member] \| Director/Stockholder [Member] \| Daniel Tierney [Member]
Related Party Transaction [Line Items]
Number of Shares Purchased	1,798
Total Purchase Price	$ 25,176
Tender Offer [Member] \| Common Class A [Member] \| Stockholder [Member] \| GA-GTCO Interholdco, LLC [Member]
Related Party Transaction [Line Items]
Number of Shares Purchased	8,285
Total Purchase Price	$ 115,989
Tender Offer [Member] \| Common Class A [Member] \| Stockholder [Member] \| Jefferies LLC [Member]
Related Party Transaction [Line Items]
Number of Shares Purchased	6,533
Total Purchase Price	$ 91,458

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30, 31

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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