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Store Divestitures (Details) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 USD ($) | Dec. 31, 2017 USD ($) store | Dec. 31, 2016 USD ($) store | Dec. 31, 2015 USD ($) store
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |
Gain on disposal | $ |  | $ 78.2 | $ 61.8 | $ 7.4
Write-downs associated with pending business divestitures | $ | $ 26.2 |  |  |
Domestic Stores Divested [Member] |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |
Number of businesses divested | store |  | 2 | 5 |
Import Stores Divested [Member] |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |
Number of businesses divested | store |  | 4 | 9 | 3

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