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Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Allowance for Doubtful Accounts [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Year | $ 12.8 | $ 13.3 | $ 10.7
Amounts Recorded in Earnings | 5.4 | 4.9 | 5.7
Adjustments | (4.7) | (5.4) | (3.1)
Balance at End of Year | 13.5 | 12.8 | 13.3
Allowance for Estimated Policy Cancellations [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Year | 7.1 | 7.4 | 6.8
Amounts Recorded in Earnings | 2.1 | 0.2 | 3.6
Adjustments | (1.8) | (0.5) | (3.0)
Balance at End of Year | 7.4 | 7.1 | 7.4
Valuation Allowance for Deferred Tax Assets [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Year | 66.8 | 52.8 | 73.7
Amounts Recorded in Earnings | 12.3 | 14.0 | (20.9)
Balance at End of Year | 79.1 | 66.8 | 52.8
Accumulated Amortization of Expiration Lists, Noncompete Agreements and Trade Names [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Year | 1,203.6 | 983.9 | 758.8
Amounts Recorded in Earnings | 264.7 | 247.2 | 240.3
Adjustments | 22.4 | (27.5) | (15.2)
Balance at End of Year | $ 1,490.7 | $ 1,203.6 | $ 983.9

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- Definition Amount of increase (decrease) in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, from adjustments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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- Definition Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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