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Commitments and Contingencies - Deferred Compensation, Environmental and Other Liabilities (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items] |  |
Employer match for each 1% of the participants contributions up to 6% of the participants contributions (as a percent) | 50.00% |
Percentage of eligible compensation up to 6% of the eligible compensation, matched 50% by employer | 1.00% |
Employer contribution limit per calendar year (as a percent of compensation) | 6.00% |
Other long-term liabilities |  |
Defined Contribution Plan Disclosure [Line Items] |  |
Deferred compensation payable | $ 5.8 | $ 4.3
Environmental Assessment and Remediation Expenses |  |
Defined Contribution Plan Disclosure [Line Items] |  |
Accrued liabilities for remediation | $ 0.0 | $ 0.0

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- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 + Details
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