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Intangible Assets Schedule of Finite-Lived Intangible Assets (Details) - USD ($)
$ in Millions
Sep. 30, 2019
Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]    
Gross $ 1,680.7 $ 1,625.0
Accumulated amortization (1,132.1) (1,087.8)
Intangible assets 548.6 537.2
Permits and leasehold agreements    
Finite-Lived Intangible Assets [Line Items]    
Gross 1,144.6 1,107.4
Accumulated amortization (725.7) (697.6)
Intangible assets 418.9 409.8
Franchise agreements    
Finite-Lived Intangible Assets [Line Items]    
Gross 489.1 470.7
Accumulated amortization (367.6) (357.1)
Intangible assets 121.5 113.6
Other intangible assets    
Finite-Lived Intangible Assets [Line Items]    
Gross 47.0 46.9
Accumulated amortization (38.8) (33.1)
Intangible assets $ 8.2 $ 13.8