Goodwill and Other Intangible Assets, Net (Finite-lived Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-lived Intangible Assets
Gross Intangible Assets, Beginning Balance	$ 775.4	$ 749.9
Gross Intangible Assets, Acquisitions	28.5	25.5
Gross Intangible Assets, Divestitures	(10.2)	0.0
Gross Intangible Assets, Ending Balance	793.7	775.4
Accumulated Amortization, Beginning Balance	(634.3)	(567.6)
Accumulated Amortization, Additions Charged to Expense	(56.8)	(66.7)
Accumulated Amortization, Divestitures	3.9	0.0
Accumulated Amortization, Ending Balance	(687.2)	(634.3)
Other Intangible Assets, Net as of December 31, 2018	106.5	141.1
Accounting Standards Update 2014-09 | Other Noncurrent Assets
Finite-lived Intangible Assets
Deferred contract costs	5.7
Customer relationships, franchise and other municipal agreements
Finite-lived Intangible Assets
Gross Intangible Assets, Beginning Balance	666.0	650.8
Gross Intangible Assets, Acquisitions	27.0	15.2
Gross Intangible Assets, Divestitures	(0.6)	0.0
Gross Intangible Assets, Ending Balance	692.4	666.0
Accumulated Amortization, Beginning Balance	(554.7)	(492.5)
Accumulated Amortization, Additions Charged to Expense	(52.5)	(62.2)
Accumulated Amortization, Divestitures	0.0	0.0
Accumulated Amortization, Ending Balance	(607.2)	(554.7)
Other Intangible Assets, Net as of December 31, 2018	85.2	111.3
Non-compete agreements
Finite-lived Intangible Assets
Gross Intangible Assets, Beginning Balance	35.6	32.1
Gross Intangible Assets, Acquisitions	1.5	3.5
Gross Intangible Assets, Divestitures	(0.1)	0.0
Gross Intangible Assets, Ending Balance	37.0	35.6
Accumulated Amortization, Beginning Balance	(28.5)	(25.3)
Accumulated Amortization, Additions Charged to Expense	(3.1)	(3.2)
Accumulated Amortization, Divestitures	0.1	0.0
Accumulated Amortization, Ending Balance	(31.5)	(28.5)
Other Intangible Assets, Net as of December 31, 2018	5.5	7.1
Other intangible assets
Finite-lived Intangible Assets
Gross Intangible Assets, Beginning Balance	73.8	67.0
Gross Intangible Assets, Acquisitions	0.0	6.8
Gross Intangible Assets, Divestitures	(9.5)	0.0
Gross Intangible Assets, Ending Balance	64.3	73.8
Accumulated Amortization, Beginning Balance	(51.1)	(49.8)
Accumulated Amortization, Additions Charged to Expense	(1.2)	(1.3)
Accumulated Amortization, Divestitures	3.8	0.0
Accumulated Amortization, Ending Balance	(48.5)	(51.1)
Other Intangible Assets, Net as of December 31, 2018	$ 15.8	$ 22.7