Acquisition - Summary of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Aug. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 4,212,523	$ 4,195,150
STP
Business Acquisition [Line Items]
Trade and other receivables			$ 243,157
Prepaid expenses and other			6,998
Property and equipment			38,732
Other long term assets			14,280
Goodwill			645,766
Customer relationships and other identifiable intangible assets			584,274
Deferred tax asset			9,365
Liabilities assumed			(315,082)
Aggregate purchase price			$ 1,227,490
Other
Business Acquisition [Line Items]
Trade and other receivables		27,810
Prepaid expenses and other		5,097
Property and equipment		992
Goodwill		28,540
Customer relationships and other identifiable intangible assets		61,823
Other intangible assets		61,823
Deferred tax asset		146
Liabilities assumed		(42,550)
Deferred tax liabilities		(5,123)
Aggregate purchase price		$ 76,735