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Fixed Assets and Lease Commitments (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
Fixed assets |  |  |
Fixed assets, at cost | $ 247.3 | $ 234.2 |
Accumulated depreciation and amortization | (136.3) | (124.1) |
Fixed assets, net | 111.0 | 110.1 | $ 114.1
Building and leasehold improvements |  |  |
Fixed assets |  |  |
Fixed assets, at cost | 111.9 | 103.5 |
Software |  |  |
Fixed assets |  |  |
Fixed assets, at cost | 50.8 | 52.5 |
Equipment |  |  |
Fixed assets |  |  |
Fixed assets, at cost | 44.5 | 39.5 |
Furniture and fixtures |  |  |
Fixed assets |  |  |
Fixed assets, at cost | 21.4 | 20.8 |
Land, improvements and other |  |  |
Fixed assets |  |  |
Fixed assets, at cost | $ 18.7 | $ 17.9 |

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- Definition Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.13) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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