Goodwill and Other Intangible Assets, Net - Other Intangible Assets, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Gross Intangible Assets
Beginning balance	$ 793.7
Acquisitions	14.2
Adjustments and Other	(5.2)
Ending balance	802.7
Accumulated Amortization
Beginning balance	(687.2)
Additions Charged to Expense	(4.8)
Adjustments and Other	4.4
Ending balance	(687.6)
Other Intangible Assets, Net	115.1	$ 106.5
Customer relationships, franchise and other municipal agreements
Gross Intangible Assets
Beginning balance	692.4
Acquisitions	11.1
Adjustments and Other	0.0
Ending balance	703.5
Accumulated Amortization
Beginning balance	(607.2)
Additions Charged to Expense	(3.7)
Adjustments and Other	0.2
Ending balance	(610.7)
Other Intangible Assets, Net	92.8
Non-compete agreements
Gross Intangible Assets
Beginning balance	37.0
Acquisitions	3.1
Adjustments and Other	0.9
Ending balance	41.0
Accumulated Amortization
Beginning balance	(31.5)
Additions Charged to Expense	(0.9)
Adjustments and Other	0.0
Ending balance	(32.4)
Other Intangible Assets, Net	8.6
Other intangible assets
Gross Intangible Assets
Beginning balance	64.3
Acquisitions	0.0
Adjustments and Other	(6.1)
Ending balance	58.2
Accumulated Amortization
Beginning balance	(48.5)
Additions Charged to Expense	(0.2)
Adjustments and Other	4.2
Ending balance	(44.5)
Other Intangible Assets, Net	$ 13.7