Acquisitions (Details Textual) - USD ($)		3 Months Ended		6 Months Ended		12 Months Ended
	May. 01, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Aug. 18, 2014	Aug. 01, 2014	Jul. 31, 2014	Jun. 03, 2014	Feb. 14, 2014	Jan. 01, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Adjustments to deferred acquisition consideration included in share-based compensation		$ 2,245	$ 2,164	$ 4,914	$ 4,285
Business Acquisition, Pro Forma Revenue		3,182		3,182
Business Acquisition, Pro Forma Net Income (Loss)		573		573
Redeemable Noncontrolling Interest, Equity, Fair Value		$ 148,401,000		148,401,000		$ 194,951,000							$ 148,534,000
Increase Decrease in Redeemable and Non Redeemable Non Controlling Interest from Step up Transactions				$ (41,932,000)
Noncontrolling Interest, Ownership Percentage by Parent		100.00%		100.00%
Aggregate 2015 Acquisitions [Member] | Y Media Labs, LLC [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 45,096
Business Acquisition, Cost of Acquired Entity, Cash Paid	20,000
Business Acquisition, Deferred Acquisition Consideration	25,096
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets	11,542
Business Acquisition, Purchase Price Allocation, Goodwill Amount	38,618
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life				5 years 1 month
Redeemable Noncontrolling Interest, Equity, Fair Value	1,999
Business Acquisition Purchase Price Allocation Intangibles and Goodwill Expected Tax Deductible Amount	$ 0
Business Acquisition, Percentage of Voting Interests Acquired	60.00%
Aggregate 2015 Step Up Transactions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price		$ 104,522		$ 104,522
Business Acquisition, Cost of Acquired Entity, Cash Paid				27,437
Business Acquisition, Deferred Acquisition Consideration		77,085		77,085
Redeemable Noncontrolling Interest, Equity, Fair Value		$ 62,616		62,616
Aggregate 2014 Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price						151,202,000
Business Acquisition, Cost of Acquired Entity, Cash Paid						67,236,000
Business Acquisition, Deferred Acquisition Consideration						83,966,000
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets						64,733,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount						146,806,000
Nonredeemable Noncontrolling Interest						50,552,000
Redeemable Noncontrolling Interest, Equity, Fair Value						13,327,000
Business Acquisition Purchase Price Allocation Intangibles and Goodwill Expected Tax Deductible Amount						149,232,000
Aggregate 2014 Acquisitions [Member] | Luntz Global Partners L L C
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired												60.00%
Aggregate 2014 Acquisitions [Member] | Kingsdale Partners LP
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired											65.00%
Aggregate 2014 Acquisitions [Member] | Hunter PR LLC [Member] [Domain]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired								65.00%
Aggregate 2014 Acquisitions [Member] | Albion Brand Communications Limited [Member] [Domain] [Domain]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired							75.00%
Aggregate 2014 Acquisitions [Member] | The House Worldwide Ltd [Member]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired										100.00%
Trapeze Media Limited | Union Advertising Canada LC [Member]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired									100.00%
Union Advertising Canada LC [Member] | Trapeze Media Limited
Business Acquisition [Line Items]
Business Combination, Step Acquisition Gain on sale of ownership percentage						$ 908,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners									18.00%
Minimum [Member] | Aggregate 2014 Acquisitions [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						5 years
Maximum [Member] | Aggregate 2014 Acquisitions [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						6 years
Noncontrolling Interest [Member]
Business Acquisition [Line Items]
Increase Decrease in Redeemable and Non Redeemable Non Controlling Interest from Step up Transactions				(8,733,000)
Noncontrolling Interest [Member] | Aggregate 2015 Step Up Transactions [Member]
Business Acquisition [Line Items]
Increase Decrease in Redeemable and Non Redeemable Non Controlling Interest from Step up Transactions				9,000
Additional Paid-in Capital [Member]
Business Acquisition [Line Items]
Increase Decrease in Redeemable and Non Redeemable Non Controlling Interest from Step up Transactions				(33,199,000)
Additional Paid-in Capital [Member] | Aggregate 2015 Step Up Transactions [Member]
Business Acquisition [Line Items]
Increase Decrease in Redeemable and Non Redeemable Non Controlling Interest from Step up Transactions				$ 33,000