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Retirement Benefit Plans - Additional Information (Details) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 USD ($) subsidiary employee plan | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Feb. 03, 2006 plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Number of non-contributory defined benefit pension plans | plan |  |  |  | 2
Estimate of amount of unrecognized actuarial expense | $ 500 |  |  |
Number of defined contribution plans | plan | 2 |  |  |
Pension Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Underfunded status | $ (1,730) | $ (1,844) |  |
Supplemental Employee Retirement Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Estimate of amount of unrecognized actuarial expense | $ 700 |  |  |
SERP credited service period | 10 years |  |  |
Percentage of final 3 year average salary in which retirement benefit is based (percentage) | 20.00% |  |  |
Number of final years in which the Retirement Benefit is based | 3 years |  |  |
Retirement age | 65 years |  |  |
Period of time that vested retirement benefit will be paid after death or change in control | 90 days |  |  |
Years of monthly installments associated with SERP disability | 15 years |  |  |
Supplemental Employee Retirement Plan | Minimum |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Current retirement benefit percentage | 10.00% |  |  |
Supplemental Employee Retirement Plan | Maximum |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Current retirement benefit percentage | 20.00% |  |  |
Employees’ Retirement Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Former employees | employee | 247 |  |  |
Current employees | employee | 55 |  |  |
IAM Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Annual contribution amount | $ 400 | 600 | $ 400 |
United States |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Annual contribution amount | 3,500 | 2,800 | 2,300 |
Foreign Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Annual contribution amount | $ 900 | $ 900 | $ 900 |
Number of international subsidiaries that participate in defined contribution and savings plan | subsidiary | 3 |  |  |
Foreign Plan | Minimum |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Employer contribution percentage | 0.00% |  |  |
Foreign Plan | Maximum |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Employer contribution percentage | 10.00% |  |  |

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- Definition Deferred Compensation Arrangement with Individual, Duration Limit Vested Retirement Benefit Will Be Paid After Death Or Change In Control + References No definition available. + Details
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- Definition Defined Benefit Plan, Number of Defined Benefit Pension Plans + References No definition available. + Details
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- Definition Defined Contribution Plan, Number of Subsidiaries + References No definition available. + Details
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- Definition Amount of cost (credit) included in accumulated other comprehensive (income) loss expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109237824&loc=d3e1703-114919 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 + 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 Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
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