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Retirement Plans (Defined Contribution Plans) (Details) - Pension Plan $ in Thousands | 12 Months Ended
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Dec. 31, 2017 USD ($) plan | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Defined Contribution Plan Disclosure |  |  |
Number of defined contribution plans | plan | 6 |  |
Defined Contribution Plan, Cost | $ | $ 3,314 | $ 2,414 | $ 3,154
CANADA |  |  |
Defined Contribution Plan Disclosure |  |  |
Number of defined contribution plans | plan | 2 |  |
Defined Contribution Plan, Cost | $ | $ 223 | 225 | 226
UNITED KINGDOM |  |  |
Defined Contribution Plan Disclosure |  |  |
Number of defined contribution plans | plan | 2 |  |
Defined Contribution Plan, Cost | $ | $ 450 | 376 | 494
UNITED STATES |  |  |
Defined Contribution Plan Disclosure |  |  |
Number of defined contribution plans | plan | 2 |  |
Defined Contribution Plan, Cost | $ | $ 2,641 | $ 1,813 | $ 2,434

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- Definition Number of defined contribution plans offered by the company. + References No definition available. + Details
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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 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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- Details
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- Details
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- Details
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- Details
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