Intangible Assets - Schedule of Finite-Lived Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross	$ 1,635.4	$ 1,633.8
Accumulated Amortization	(1,015.0)	(1,000.6)
Net	620.4us-gaap_FiniteLivedIntangibleAssetsNet	633.2us-gaap_FiniteLivedIntangibleAssetsNet
Permits and leasehold agreements
Finite-Lived Intangible Assets [Line Items]
Gross	1,121.8	1,119.2
Accumulated Amortization	(685.3)	(677.2)
Net	436.5	442.0
Franchise agreements
Finite-Lived Intangible Assets [Line Items]
Gross	473.7	474.7
Accumulated Amortization	(325.7)	(321.1)
Net	148.0	153.6
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross	39.9	39.9
Accumulated Amortization	(4.0)	(2.3)
Net	$ 35.9	$ 37.6

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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