Business Acquisitions and Divestitures (Details) $ / shares in Units, $ in Thousands, € in Millions					9 Months Ended	12 Months Ended
	May 15, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 27, 2016 USD ($)	Oct. 02, 2015 USD ($)	Oct. 02, 2015 USD ($)	Dec. 31, 2017 USD ($) acquisition	Dec. 31, 2016 USD ($) business	Dec. 31, 2015 USD ($) business	Nov. 17, 2017 $ / shares	Sep. 15, 2017	Aug. 04, 2017	Oct. 31, 2016	Apr. 01, 2016	Jan. 07, 2016	Oct. 26, 2015	Oct. 21, 2015	Oct. 02, 2015 EUR (€)	Oct. 02, 2015 USD ($)	Sep. 01, 2015	Jul. 20, 2015	Mar. 04, 2015	Feb. 09, 2015	Jan. 21, 2015
Business Acquisition [Line Items]
Number of businesses acquired						4	6
Consideration transferred						$ 152,000
Goodwill acquired						82,659	$ 2,876,991
Identifiable intangibles						85,000
Goodwill		$ 8,647,142				8,820,313	8,647,142	$ 5,824,726
Acquisition-related Costs
Business Acquisition [Line Items]
Pro forma earnings							$ 47,400
Energy Systems & Controls | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Business Acquisition [Line Items]
Consideration received on disposal	$ 10,400
Gain on disposal	$ 9,400
Abel Pumps LP | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Business Acquisition [Line Items]
Consideration received on disposal																	€ 95	$ 106,000
Gain on disposal				$ 70,900
Tax expense related to gain on disposal group				46,000
Future tax benefit related to sale of disposal group				$ 11,000
Year to date income of disposal group prior to disposal					$ 5,900
Customer related intangibles
Business Acquisition [Line Items]
Finite-lived intangibles						$ 68,000
Weighted average useful life of finite-lived intangible assets						15 years
Unpatented technology
Business Acquisition [Line Items]
Finite-lived intangibles						$ 13,000
Weighted average useful life of finite-lived intangible assets						6 years
Handshake Software, Inc.
Business Acquisition [Line Items]
Percentage of voting interests acquired											100.00%
Workbook Software A/S
Business Acquisition [Line Items]
Percentage of voting interests acquired										100.00%
Onvia
Business Acquisition [Line Items]
Percentage of voting interests acquired									100.00%
Share price | $ / shares									$ 9.00
Deltek
Business Acquisition [Line Items]
Consideration transferred			$ 2,800,000
Percentage of voting interests acquired			100.00%
Identifiable intangibles			$ 972,000			$ 972,000
Finite-lived intangibles						$ 765,000
Weighted average useful life of finite-lived intangible assets						12 years
Indefinite-lived intangible assets						$ 145,000
Transaction costs						4,300
Revenue of acquiree since acquisition date		7,900
Earnings or loss of acquiree since acquisition date		800
Goodwill			$ 2,234,549
Deltek | Customer related intangibles
Business Acquisition [Line Items]
Finite-lived intangibles						$ 625,000
Weighted average useful life of finite-lived intangible assets						13 years
Deltek | Unpatented technology
Business Acquisition [Line Items]
Finite-lived intangibles						$ 140,000
Weighted average useful life of finite-lived intangible assets						6 years
Deltek | In process research and development
Business Acquisition [Line Items]
Finite-lived intangibles						$ 62,000
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Number of businesses acquired | business							5	8
Consideration transferred							$ 920,000	$ 1,800,000
Identifiable intangibles		372,000					372,000	731,000
Finite-lived intangibles		338,000					$ 338,000	$ 680,000
Weighted average useful life of finite-lived intangible assets							12 years	17 years
Indefinite-lived intangible assets		34,000					$ 34,000	$ 51,000
Transaction costs		4,200					4,200	5,900
Goodwill		642,000					642,000	1,200,000
Series of Individually Immaterial Business Acquisitions | Customer related intangibles
Business Acquisition [Line Items]
Finite-lived intangibles		242,000					$ 242,000	$ 541,000
Weighted average useful life of finite-lived intangible assets							14 years	19 years
Series of Individually Immaterial Business Acquisitions | Unpatented technology
Business Acquisition [Line Items]
Finite-lived intangibles		66,000					$ 66,000	$ 100,000
Weighted average useful life of finite-lived intangible assets							6 years	8 years
Series of Individually Immaterial Business Acquisitions | Software
Business Acquisition [Line Items]
Finite-lived intangibles		$ 30,000					$ 30,000	$ 39,000
Weighted average useful life of finite-lived intangible assets							9 years	6 years
CliniSys
Business Acquisition [Line Items]
Percentage of voting interests acquired														100.00%
GeneInsight Inc.
Business Acquisition [Line Items]
Percentage of voting interests acquired													100.00%
ConstructConnect
Business Acquisition [Line Items]
Percentage of voting interests acquired												100.00%
Strata
Business Acquisition [Line Items]
Percentage of voting interests acquired																							100.00%
Softwriters Inc.
Business Acquisition [Line Items]
Percentage of voting interests acquired																						100.00%
Data Innovations LLC
Business Acquisition [Line Items]
Percentage of voting interests acquired																					100.00%
Atlas
Business Acquisition [Line Items]
Percentage of voting interests acquired															100.00%
On Center
Business Acquisition [Line Items]
Percentage of voting interests acquired																				100.00%
RF IDeas, Inc.
Business Acquisition [Line Items]
Percentage of voting interests acquired																			100.00%
Aderant
Business Acquisition [Line Items]
Percentage of voting interests acquired																100.00%