Goodwill and Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Beginning Balance	$ 835,935	$ 844,759
Acquired goodwill	37,592	0
Disposition		(17,593)
Impairment loss recognized	(74,560)	(3,238)
Transfer of goodwill between segments	0	0
Transfer of goodwill to asset held for sale	(45,224)
Foreign currency translation	(12,788)	12,007
Ending Balance	740,955	835,935
Media Services [Member]
Goodwill [Roll Forward]
Beginning Balance	160,057	176,686
Acquired goodwill	0	0
Disposition		16,629
Impairment loss recognized	(52,041)	(497)
Transfer of goodwill between segments	3,773	497
Transfer of goodwill to asset held for sale	0
Foreign currency translation	(443)	0
Ending Balance	111,346	160,057
All Other [Domain]
Goodwill [Roll Forward]
Beginning Balance	201,121	201,904
Acquired goodwill	32,776
Disposition		0
Impairment loss recognized	(4,691)	0
Transfer of goodwill between segments	(22,920)	(6,868)
Transfer of goodwill to asset held for sale	(45,224)
Foreign currency translation	(6,891)	6,085
Ending Balance	154,171	201,121
Global Integrated Agencies [Member]
Goodwill [Roll Forward]
Beginning Balance	359,071	350,716
Acquired goodwill	0	0
Disposition		964
Impairment loss recognized	(17,828)	(2,741)
Transfer of goodwill between segments	17,081	6,371
Transfer of goodwill to asset held for sale	0
Foreign currency translation	(5,169)	5,689
Ending Balance	353,155	359,071
Domestic Creative Agencies [Member]
Goodwill [Roll Forward]
Beginning Balance	36,980	36,762
Acquired goodwill	0	0
Disposition		0
Impairment loss recognized	0	0
Transfer of goodwill between segments	2,066	0
Transfer of goodwill to asset held for sale	0
Foreign currency translation	(266)	218
Ending Balance	38,780	36,980
Specialist Communications [Member]
Goodwill [Roll Forward]
Beginning Balance	78,706	78,691
Acquired goodwill	4,816	0
Disposition		0
Impairment loss recognized	0	0
Transfer of goodwill between segments	0	0
Transfer of goodwill to asset held for sale	0
Foreign currency translation	(19)	15
Ending Balance	$ 83,503	$ 78,706

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Amount of transfers into (out of) an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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