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Intangible Assets - Major Classes of Amortizable Intangible Assets (Detail) - USD ($) $ in Millions | Sep. 30, 2021 | Dec. 31, 2020
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Finite-Lived Intangible Assets [Line Items] |  |
Amortizable intangible assets, net | $ 2,339.0 | $ 2,399.9
Expiration Lists [Member] |  |
Finite-Lived Intangible Assets [Line Items] |  |
Amortizable intangible assets, gross | 4,997.2 | 4,753.2
Accumulated amortization | (2,727.5) | (2,436.7)
Amortizable intangible assets, net | 2,269.7 | 2,316.5
Non-Compete Agreements [Member] |  |
Finite-Lived Intangible Assets [Line Items] |  |
Amortizable intangible assets, gross | 73.5 | 75.9
Accumulated amortization | (61.9) | (57.8)
Amortizable intangible assets, net | 11.6 | 18.1
Trade Names [Member] |  |
Finite-Lived Intangible Assets [Line Items] |  |
Amortizable intangible assets, gross | 105.5 | 107.8
Accumulated amortization | (47.8) | (42.5)
Amortizable intangible assets, net | $ 57.7 | $ 65.3

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