Discontinued Operations Gracenote Companies Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Jan. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents	$ 0		$ 12,751	$ 14,824
Total current assets of discontinued operations	0		62,605
Total non-current assets of discontinued operations	0		608,153
Total current liabilities of discontinued operations	0		54,284
Total non-current liabilities of discontinued operations	$ 0		95,314
Gracenote Companies | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents		$ 17,000	12,751
Accounts receivable, net			38,727
Prepaid expenses and other			11,127
Total current assets of discontinued operations			62,605
Property, plant and equipment, net			49,348
Goodwill			333,258
Other intangible assets, net			219,287
Other long-term assets			6,260
Total non-current assets of discontinued operations			608,153
Total Assets Classified as Discontinued Operations in the Consolidated Balance Sheets			670,758
Accounts payable			6,237
Employee compensation and benefits			17,011
Deferred revenue			27,113
Accrued expenses and other current liabilities			3,923
Total current liabilities of discontinued operations			54,284
Deferred income taxes			89,029
Postretirement, medical, life and other benefits			2,786
Other obligations			3,499
Total non-current liabilities of discontinued operations			95,314
Total Liabilities Classified as Discontinued Operations in the Consolidated Balance Sheets			149,598
Net Assets Classified as Discontinued Operations			$ 521,160