Acquisitions Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended		12 Months Ended
	May 31, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired		$ 0	$ 69,974
Infostrada, SportsDirect, Covers, Enswers
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired	$ 69,849
Transaction costs				$ 3,000
Intangible assets, useful life (years)	12 years
Infostrada, SportsDirect, Covers, Enswers | Customer Relationships
Business Acquisition [Line Items]
Intangible assets, useful life (years)	11 years
Infostrada, SportsDirect, Covers, Enswers | Content Databases
Business Acquisition [Line Items]
Intangible assets, useful life (years)	14 years
Infostrada, SportsDirect, Covers, Enswers | Technologies
Business Acquisition [Line Items]
Intangible assets, useful life (years)	8 years
Infostrada, SportsDirect, Covers, Enswers | Trade Name and Trademarks
Business Acquisition [Line Items]
Intangible assets, useful life (years)	15 years
Infostrada, SportsDirect, Covers, Enswers | Non-competition Agreements
Business Acquisition [Line Items]
Intangible assets, useful life (years)	5 years