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Intangible Assets - Major Classes of Amortizable Intangible Assets (Detail) - USD ($) $ in Millions | Jun. 30, 2018 | Dec. 31, 2017
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Finite-Lived Intangible Assets [Line Items] |  |  |
Amortizable intangible assets, net | $ 1,731.0 | $ 1,644.6 | [1]
Expiration Lists [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortizable intangible assets, gross | 3,233.4 | 3,055.9 |
Accumulated amortization | (1,547.5) | (1,422.1) |
Amortizable intangible assets, net | 1,685.9 | 1,633.8 |
Non-Compete Agreements [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortizable intangible assets, gross | 54.9 | 53.5 |
Accumulated amortization | (47.4) | (46.1) |
Amortizable intangible assets, net | 7.5 | 7.4 |
Trade Names [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Amortizable intangible assets, gross | 60.6 | 25.9 |
Accumulated amortization | (23.0) | (22.5) |
Amortizable intangible assets, net | $ 37.6 | $ 3.4 |
[1] | See Note 3 - Revenues from Contracts with Customers for additional information about the restatements related to ASC 606.

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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://fasb.org/us-gaap/role/ref/legacyRef -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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