Acquisitions - Additional Information (Details) - USD ($) $ in Thousands					3 Months Ended		6 Months Ended
	Apr. 14, 2016	Nov. 20, 2015	Nov. 06, 2015	May 19, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Business Acquisition [Line Items]
Escrow funding associated with acquisition							$ 0	$ 78,694
Gain on derivative instruments					$ 0	$ 85,187	0	85,187
Interest expense					31,435	37,662	63,467	55,924
Current portion of escrow					4,856		4,856		$ 38,656
Escrow deposit					$ 0		$ 0		$ 4,591
RII
Business Acquisition [Line Items]
Percent of corporate wholly-owned subsidiaries	100.00%
Net cash purchase price	$ 6,200
Wood Mackenzie
Business Acquisition [Line Items]
Percent of corporate wholly-owned subsidiaries				100.00%
Net cash purchase price				$ 2,889,629
Escrow funding associated with acquisition				$ 78,694
Gain on derivative instruments						$ 85,187		85,187
Transaction costs								26,617
Interest expense								$ 13,336
Infield
Business Acquisition [Line Items]
Percent of corporate wholly-owned subsidiaries			100.00%
Net cash purchase price			$ 13,804
PCI
Business Acquisition [Line Items]
Percent of corporate wholly-owned subsidiaries		100.00%
Net cash purchase price		$ 37,387