Business Acquisitions - Narrative (Details) - USD ($)		9 Months Ended	12 Months Ended
	Feb. 02, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 28, 2018	Jan. 31, 2018
Business Acquisition [Line Items]
Acquisitions, net of cash acquired			$ 1,118,000,000	$ 184,100,000	$ 173,400,000
Goodwill			1,784,400,000	1,089,000,000	$ 991,000,000
Aclara
Business Acquisition [Line Items]
Total Aclara Transaction Costs			12,800,000	$ 7,100,000
Consideration transferred to acquire business	$ 1,100,000,000
Goodwill	708,700,000
Deductible goodwill	159,900,000
Contributed sales		$ 611,100,000
Contributed operating income		$ 29,600,000
Immaterial business acquisitions
Business Acquisition [Line Items]
Deferred purchase price and net working capital settlements			$ 1,700,000
Term Loan Agreement | Line of Credit
Business Acquisition [Line Items]
Line of credit, maximum borrowing capacity	$ 500,000,000						$ 500,000,000
Notes 2028 Term | Senior Notes
Business Acquisition [Line Items]
Senior notes, stated percentage	3.50%		3.50%			3.50%
Face amount	$ 450,000,000					$ 450,000,000