|**Self-Insured Risks Self-Insured Risks (Tables)** | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
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|**Insurance [Abstract]**                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Self-Insurance Reserves                            | The following table presents the changes in our self-insurance reserves for the years endedDecember 31, 2016,2015, and2014(in millions):201620152014Balance at beginning of period, gross$142.1$134.3$140.3Less: Reinsurance receivables(26.6)(26.0)(32.6)Balance at beginning of period, net115.5108.3107.7Increase for the provision of current year claims43.537.134.7Decrease for the provision of prior year claims(0.1)(4.6)(3.5)Expenses related to discontinued operations(0.4)(0.5)(0.3)Payments related to current year claims(5.0)(4.7)(4.4)Payments related to prior year claims(23.5)(22.5)(25.9)Acquisitions—2.4—Balance at end of period, net130.0115.5108.3Add: Reinsurance receivables41.426.626.0Balance at end of period, gross$171.4$142.1$134.3
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|                                                   | 2016                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Balance at beginning of period, gross              | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Less: Reinsurance receivables                      | (26.6                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|Balance at beginning of period, net                | 115.5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|Increase for the provision of current year claims  | 43.5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Decrease for the provision of prior year claims    | (0.1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Expenses related to discontinued operations        | (0.4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Payments related to current year claims            | (5.0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Payments related to prior year claims              | (23.5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|Acquisitions                                       | —                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Balance at end of period, net                      | 130.0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|Add: Reinsurance receivables                       | 41.4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Balance at end of period, gross                    | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

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duration X- DefinitionTabular disclosure of the activity in the reserve for settling insured claims and expenses incurred in the claims settlement process for the period. The estimated liability includes the amount of money that will be required for future payments of (a) claims that have been reported to the insurer, (b) claims related to insured events that have occurred but that have not been reported to the insurer as of the date the liability is estimated, and (c) claim adjustment expenses. Claim adjustment expenses include costs incurred in the claim settlement process such as legal fees; outside adjuster fees; and costs to record, process, and adjust claims.
+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437
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