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Defined Benefit Plans - Narrative (Details) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 USD ($) plan | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
UNITED STATES |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Estimated unrecognized loss that will be amortized from AOCI, net of income taxes | $ 200 |  |
Number of plans | plan | 3 |  |
Benefit obligation | $ 9,200 | $ 9,200 |
Fair value of plan assets | $ 6,000 | $ 5,700 |
Annual rate of return on plan assets | 7.00% | 7.00% |
Estimated future benefit payments | $ 500 |  |
Net periodic pension cost (income) | $ 300 | $ 300 | $ 300
Minimum | UNITED STATES |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Discount rate | 2.00% | 3.00% |
Maximum | UNITED STATES |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Discount rate | 2.25% | 4.00% |
United Kingdom Subsidiary | UK Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Underfunded status of UK Plan | $ 35,731 | $ 15,765 |
Annual rate of inflation | 2.50% | 2.00% |
Average life expectancy | 24 years |  |
Estimated unrecognized loss that will be amortized from AOCI, net of income taxes | $ 2,900 |  |
Future estimated employer contributions to be paid next year | 5,000 |  |
Benefit obligation | 383,142 | $ 322,766 | 281,776
Fair value of plan assets | $ 347,411 | $ 307,001 | $ 264,194
Discount rate | 1.40% | 2.10% |
Annual rate of return on plan assets | 4.30% | 4.90% | 5.00%
Net periodic pension cost (income) | $ (3,233) | $ (1,862) | $ (3,082)
Selling, General and Administrative Expenses | UNITED STATES |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Reclassification adjustment from AOCI, net of income taxes | 300 | 200 | 200
Selling, General and Administrative Expenses | United Kingdom Subsidiary | UK Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Reclassification adjustment from AOCI, net of income taxes | 1,900 | 1,900 | $ 2,100
Other Noncurrent Liabilities | United Kingdom Subsidiary | UK Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Underfunded status of UK Plan | $ 35,700 | $ 15,800 |

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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2919-114920 + Details
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- Definition Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: 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 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -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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