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Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
SEC Schedule, 12-09, Allowance, Credit Loss [Member] |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Year | $ 10.0 | $ 13.5 | $ 12.8
Amounts Recorded in Earnings | 4.2 | 5.8 | 5.4
Adjustments | (5.5) | (9.3) | (4.7)
Balance at End of Year | 8.7 | 10.0 | 13.5
Allowance for Estimated Policy Cancellations [Member] |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Year | 7.8 | 7.4 | 7.1
Amounts Recorded in Earnings | 0.5 | (1.2) | 2.1
Adjustments |  | 1.6 | (1.8)
Balance at End of Year | 8.3 | 7.8 | 7.4
Valuation Allowance for Deferred Tax Assets [Member] |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Year | 67.4 | 79.1 | 66.8
Amounts Recorded in Earnings | 13.1 | (11.7) | 12.3
Balance at End of Year | 80.5 | 67.4 | 79.1
Accumulated Amortization of Expiration Lists, Noncompete Agreements and Trade Names [Member] |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Year | 1,750.4 | 1,490.7 | 1,203.6
Amounts Recorded in Earnings | 334.0 | 291.3 | 264.7
Adjustments | 3.1 | (31.6) | 22.4
Balance at End of Year | $ 2,087.5 | $ 1,750.4 | $ 1,490.7

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