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Employee Benefit Plans - Narrative (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2018 USD ($) Employees | Mar. 31, 2018 | Dec. 31, 2017 USD ($) | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 USD ($) | Jun. 30, 2016 | Mar. 31, 2016
Multiemployer Plans, Pension [Member] |  |  |  |  |  |  |  |
Number Of Local Unions | Employees | 100 |  |  |  |  |  |  |
Multiemployer Plans Red Zone Funded Status Percentage | 65.00% |  |  |  |  |  |  |
Multiemployer Plans Green Zone Funded Status Percentage | 80.00% |  |  |  |  |  |  |
Multiemployer Plans, Pension [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Multiemployer Plans Yellow Zone Funded status Percentage | 80.00% |  |  |  |  |  |  |
Multiemployer Plans, Pension [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Multiemployer Plans Yellow Zone Funded status Percentage | 65.00% |  |  |  |  |  |  |
Eighth District Electrical Pension Fund [Member] | Multiemployer Plans, Pension [Member] |  |  |  |  |  |  |  |
Multiemployer Plan, Collective-Bargaining Arrangement, Required Percentage of Contributions |  | 5.00% |  |  | 5.00% |  |  | 5.00%
IBEW Local 769 Management Pension Plan A [Member] | Multiemployer Plans, Pension [Member] |  |  |  |  |  |  |  |
Multiemployer Plan, Collective-Bargaining Arrangement, Required Percentage of Contributions |  |  |  | 5.00% |  |  | 5.00% |
Other Postretirement Benefits Plan [Member] | Foreign Plan [Member] | Retirement Saving Plan [Member] |  |  |  |  |  |  |  |
Defined Contribution Plan, Cost | $ 0.1 |  | $ 0.1 |  |  |  |  |
Other Postretirement Benefits Plan [Member] | UNITED STATES | Profit Sharing And Thrift Employee Benefit Plan [Member] |  |  |  |  |  |  |  |
Defined Contribution Plan, Cost | 4.7 |  | 3.4 |  |  | $ 4.6 |  |
Other Postretirement Benefits Plan [Member] | UNITED STATES | Employee Benefit Plan [Member] |  |  |  |  |  |  |  |
Defined Contribution Plan, Cost | $ 1.0 |  | $ 0.6 |  |  | $ 0.6 |  |

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- Definition Represents the percentage funded for green zone status. + References No definition available. + Details
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- Definition Represents the percentage funded for red zone status. + References No definition available. + Details
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- Definition Represents the percentage funded for yellow zone status. + References No definition available. + Details
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- Definition Represents the number of local unions. + References No definition available. + Details
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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Definition Percentage of contributions required by collective bargaining arrangement to all contributions required of employer for pension and other postretirement plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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- Details
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