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Intangible Assets - Major Classes of Amortizable Intangible Assets (Detail) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortizable intangible assets, net | $ 1,644.6 | $ 1,627.3 | $ 1,698.8
Expiration Lists [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortizable intangible assets, gross | 3,055.9 | 2,757.6 |
Accumulated amortization | (1,422.1) | (1,143.0) |
Amortizable intangible assets, net | 1,633.8 | 1,614.6 |
Non-Compete Agreements [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortizable intangible assets, gross | 53.5 | 49.3 |
Accumulated amortization | (46.1) | (42.1) |
Amortizable intangible assets, net | 7.4 | 7.2 |
Trade Names [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortizable intangible assets, gross | 25.9 | 24.0 |
Accumulated amortization | (22.5) | (18.5) |
Amortizable intangible assets, net | $ 3.4 | $ 5.5 |

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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References 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=66006027&loc=d3e16323-109275 + Details
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- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References 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=66006027&loc=d3e16323-109275 + Details
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- Definition Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph ((a)(1),(b)) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
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