Supplemental Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued media	$ 151,143		$ 151,143		$ 180,586
Goodwill	743,582		743,582		$ 740,955
Income tax expense (benefit)	2,088	$ 1,977	2,835	$ (6,353)
Income (loss) before income taxes and equity in earnings of non-consolidated affiliates	$ 9,215	$ 7,956	$ 10,195	$ (28,979)
Effective tax rate (percent)			22.70%	24.80%

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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