Discontinued Operations Narrative (Details) - USD ($)			3 Months Ended	9 Months Ended
	Feb. 01, 2017	Jan. 31, 2017	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Gain) Loss on Disposition of Business				$ 34,510,000	$ 0
Repayments of Long-term Debt				703,527,000	20,881,000
Amended Secured Credit Facility | Term B Loans
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Repayments of Long-term Debt	$ 400,000,000
Discontinued Operations, Disposed of by Sale | Gracenote Companies
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Consideration		$ 560,000,000
Proceeds from Divestiture of Businesses		$ 581,000,000		584,000,000
Proceeds from Divestiture of Business, Working Capital Adjustment			$ 3,000,000
(Gain) Loss on Disposition of Business				(35,000,000)
Disposal Group, Including Discontinued Operation, Legal and Professional Fees				10,000,000	$ 1,000,000
Discontinued Operation, Amounts of Material Contingent Liabilities Remaining				$ 0