Acquisitions	3 Months Ended
Mar. 31, 2017
Business Combinations [Abstract]
Acquisitions	Acquisitions On March 9, 2017, the Company acquired 100% of the outstanding capital stock of L2, Inc., ("L2"), a privately-held firm based in New York City with 150 employees, for a total purchase price of $155.0 million. L2 is a subscription-based research business that benchmarks the digital performance of brands. The Company paid $134.2 million in cash at close; but net of cash acquired with the business and for cash flow reporting purposes, the Company paid $129.3 million in cash. In addition, the Company may also be required to pay up to an additional $20.8 million in cash contingent on the achievement of certain employment conditions by several key employees of L2, which will be recognized as compensation expense over approximately three years. The Company recorded $124.7 million of goodwill and amortizable intangible assets for L2 and $9.5 million of other assets on a net basis. The operating results and the related goodwill are being reported as part of the Company's Research segment and goodwill resulting from the acquisition will not be deductible for tax purposes. The allocation of the purchase price is preliminary with respect to the valuation of finite-lived intangible assets, which the Company expects to complete in the second quarter of 2017. The Company believes the recorded goodwill is supported by the anticipated revenue synergies resulting from the acquisition. The Company's financial statements include the operating results of L2 beginning on its acquisition date, which were not material to either the Company's consolidated operating results or segment results for the first quarter of 2017. Had the Company acquired this business in prior periods, the impact to the Company's operating results for prior periods would not have been material, and as a result pro forma financial information for prior periods has not been presented.

Acquisitions

3 Months Ended

Mar. 31, 2017

On March 9, 2017, the Company acquired 100% of the outstanding capital stock of L2, Inc., ("L2"), a privately-held firm based in New York City with 150 employees, for a total purchase price of $155.0 million. L2 is a subscription-based research business that benchmarks the digital performance of brands. The Company paid $134.2 million in cash at close; but net of cash acquired with the business and for cash flow reporting purposes, the Company paid $129.3 million in cash. In addition, the Company may also be required to pay up to an additional $20.8 million in cash contingent on the achievement of certain employment conditions by several key employees of L2, which will be recognized as compensation expense over approximately three years.

The Company recorded $124.7 million of goodwill and amortizable intangible assets for L2 and $9.5 million of other assets on a net basis. The operating results and the related goodwill are being reported as part of the Company's Research segment and goodwill resulting from the acquisition will not be deductible for tax purposes. The allocation of the purchase price is preliminary with respect to the valuation of finite-lived intangible assets, which the Company expects to complete in the second quarter of 2017. The Company believes the recorded goodwill is supported by the anticipated revenue synergies resulting from the acquisition. The Company's financial statements include the operating results of L2 beginning on its acquisition date, which were not material to either the Company's consolidated operating results or segment results for the first quarter of 2017. Had the Company acquired this business in prior periods, the impact to the Company's operating results for prior periods would not have been material, and as a result pro forma financial information for prior periods has not been presented.