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Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
SEC Schedule, 12-09, Allowance, Credit Loss [Member] |  |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |
Balance at Beginning of Year |  | $ 8.3 | $ 10.1 | $ 8.7
Amounts Recorded in Earnings |  | 6.8 | 7.0 | 6.6
Adjustments | [1] | (4.0) | (8.8) | (5.2)
Balance at End of Year |  | 11.1 | 8.3 | 10.1
Allowance for Estimated Policy Cancellations [Member] |  |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |
Balance at Beginning of Year |  | 10.0 | 9.9 | 8.3
Amounts Recorded in Earnings |  | 2.4 | (1.3) | 4.1
Adjustments | [2] | (3.1) | 1.4 | (2.5)
Balance at End of Year |  | 9.3 | 10.0 | 9.9
Valuation Allowance for Deferred Tax Assets [Member] |  |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |
Balance at Beginning of Year |  | 154.9 | 94.9 | 80.5
Amounts Recorded in Earnings |  | (19.7) | 60.0 | 14.4
Balance at End of Year |  | 135.2 | 154.9 | 94.9
Accumulated Amortization of Expiration Lists, Non-compete Agreements and Trade Names [Member] |  |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |
Balance at Beginning of Year |  | 2,924.0 | 2,537.0 | 2,087.5
Amounts Recorded in Earnings |  | 454.9 | 415.1 | 417.3
Adjustments | [3] | (78.9) | (28.1) | 32.2
Balance at End of Year |  | $ 3,300.0 | $ 2,924.0 | $ 2,537.0
[1] | Net activity of bad debt write offs and recoveries and acquired businesses.
[2] | Additions to allowance related to acquired businesses.
[3] | Elimination of fully amortized expiration lists, non-compete agreements and trade names, intangible asset/amortization reclassifications and disposal of acquired businesses.

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