Acquisitions and Discontinued Operations Acquisitions (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Feb. 28, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Acquisitions, net of cash acquired		$ 284.5	$ 0.9
Goodwill		$ 2,261.0		$ 2,072.7
Aquion
Business Acquisition [Line Items]
Acquisitions, net of cash acquired	$ 163.4
Goodwill	94.5
Business Acquisition, Goodwill, Expected Tax Deductible Amount	4.6
Indefinite-lived trade name intangible assets	15.7
Definite-lived customer relationships	$ 78.8
Estimated useful life	15 years
Pelican
Business Acquisition [Line Items]
Acquisitions, net of cash acquired	$ 121.1
Goodwill	121.0
Business Acquisition, Goodwill, Expected Tax Deductible Amount	$ 7.6