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Benefit Plans, Investment Strategies (Details) | 12 Months Ended
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Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items] |
Average rate of return on assets | 9.00%
Equity Securities [Member] | Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target long-term investment portfolio mix | 55.00%
Equity Securities [Member] | Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target long-term investment portfolio mix | 65.00%
Fixed Income Securities [Member] | Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target long-term investment portfolio mix | 30.00%
Fixed Income Securities [Member] | Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target long-term investment portfolio mix | 35.00%
Other Securities [Member] | Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target long-term investment portfolio mix | 0.00%
Other Securities [Member] | Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target long-term investment portfolio mix | 15.00%

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- Definition The weighted average return on plan assets calculated based on the average number of years specified. + References No definition available. + 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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- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(5)(i) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Details
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