Discontinued Operations Gracenote Companies Statement of Operations (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Discontinued Operations, net of taxes		$ (619)	$ 0	$ (579)	$ 15,618	$ (51,776)	$ (8,074)	$ (8,935)	$ (4,009)	$ 14,420		$ (72,794)	$ (4,581)
Gracenote Companies | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues										18,168	[1]	225,903	209,964
Direct operating expenses										7,292	[1]	75,457	59,789
Selling, general and administrative										15,349	[1]	110,713	104,968
Depreciation (2)										0	[1],[2]	13,584	9,735
Amortization (2)										0	[1],[2]	29,999	28,826
Operating (loss) profit										(4,473)	[1]	(3,850)	6,646
Interest income										16	[1]	96	109
Interest expense (3)	[3]									(1,261)	[1]	(15,317)	(15,843)
Other non-operating gain, net										0	[1]	0	912
Loss before income taxes										(5,718)	[1]	(19,071)	(8,176)
Pretax gain on the disposal of discontinued operations										33,492	[1]	0	0
Total pretax gain (loss) on discontinued operations										27,774	[1]	(19,071)	(8,176)
Income tax expense (benefit) (4)	[4]									13,354	[1]	53,723	(3,595)
Income (Loss) from Discontinued Operations, net of taxes										$ 14,420	[1]	$ (72,794)	$ (4,581)

[1] Results of operations for the Gracenote Companies are reflected through January 31, 2017, the date of the Gracenote Sale.

[2] No depreciation expense or amortization expense was recorded by the Company in 2017 as the Gracenote Companies’ assets were held for sale as of December 31, 2016.

[3] The Company used $400 million of proceeds from the Gracenote Sale to prepay a portion of its outstanding borrowings under the Company’s Term Loan Facility (as defined and described in Note 9). Interest expense associated with the Company’s outstanding Term Loan Facility was allocated to discontinued operations based on the ratio of the $400 million prepayment to the total outstanding indebtedness under the Term Loan Facility in effect in each respective period.

[4] In the fourth quarter of 2016, as a result of meeting all criteria under ASC Topic 205 to classify Gracenote Companies as discontinued operations, the Company recorded tax expense of $62 million to increase the Company’s deferred tax liability for the outside basis difference related to the Gracenote Companies included in the Gracenote Sale. This charge was required to be recorded in the period the Company signed a definitive agreement to divest the business. Exclusive of this $62 million charge, the effective tax rates on pretax income from discontinued operations was 48.1%, 45.0% and 44.0% for the years ended December 31, 2017, December 31, 2016, and December 31, 2015, respectively. These rates differ from the U.S. federal statutory rate of 35% primarily due to state income taxes (net of federal benefit), foreign tax rate differences, and the impact of certain nondeductible transaction costs and other adjustments.