Segment Information (Details 1) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) reportable_segment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | reportable_segment			4
Net Income (Loss) Attributable to Parent	$ 18,493	$ (32,140)	$ 19,180	$ (54,937)
Depreciation, Depletion and Amortization, Nonproduction	11,252	11,412	32,916	34,068
Share-based Compensation	6,380	5,228	16,870	15,443
Revenue	375,800	349,254	1,111,032	995,343
Income (Loss) from Equity Method Investments	1,422	70	1,924	9
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	21,984	(31,081)	25,768	(51,765)
Net Income (Loss) Attributable to Noncontrolling Interest	3,491	1,059	6,588	3,172	$ 5,218
Cost of Services	249,418	235,659	754,803	675,940
General and Administrative Expense	77,910	83,303	251,313	233,840
Operating Income (Loss)	37,220	(10,751)	72,000	21,864
Other Nonoperating Income (Expense)	8,649	(6,008)	17,812	9,530
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	29,611	(33,081)	41,503	(50,594)
Income Tax Expense (Benefit)	9,049	(1,930)	17,659	1,180
Income Loss From Continuing Operations Before Equity In Earnings Of Non-consolidated Affiliates	20,562	(31,151)	23,844	(51,774)
Payments to Acquire Property, Plant, and Equipment	7,149	6,274	28,305	19,723
United States [Member]
Segment Reporting Information [Line Items]
Revenue	289,702	274,506	868,847	799,696
Canada [Member]
Segment Reporting Information [Line Items]
Revenue	31,418	30,233	88,471	92,253
Other Regions [Member]
Segment Reporting Information [Line Items]
Revenue	54,680	44,515	153,714	103,394
Domestic Creative Agencies [Member]
Segment Reporting Information [Line Items]
Share-based Compensation	177	150	502	487
Revenue	24,173	22,181	67,473	66,274
Operating Income (Loss)	5,716	4,688	13,563	14,779
Payments to Acquire Property, Plant, and Equipment	324	222	874	920
Specialized Communications [Member]
Segment Reporting Information [Line Items]
Share-based Compensation	659	564	2,264	1,556
Revenue	40,670	40,309	125,470	123,006
Operating Income (Loss)	4,775	11,101	13,410	17,860
Payments to Acquire Property, Plant, and Equipment	206	56	673	2,183
Media Services [Member]
Segment Reporting Information [Line Items]
Share-based Compensation	150	70	464	187
Revenue	33,027	34,481	103,966	96,681
Operating Income (Loss)	2,421	466	8,618	3,510
Payments to Acquire Property, Plant, and Equipment	2,171	2,008	3,455	2,634
All Other [Member]
Segment Reporting Information [Line Items]
Share-based Compensation	1,077	949	2,149	2,124
Revenue	83,951	75,021	237,188	219,502
Operating Income (Loss)	15,213	(22,828)	31,626	(5,619)
Payments to Acquire Property, Plant, and Equipment	$ 2,497	$ 985	$ 5,660	$ 3,251