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Income Taxes - Reconciliation of statutory to effective income tax rate (Details) | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount [Abstract] |  |  |
Federal Statutory Rate | 21.00% | 21.00% | 21.00%
Permanent differences | (1.20%) | (13.10%) | (25.70%)
State taxes, net of Federal benefit | 0.00% | (0.10%) | 3.50%
Rate change | (0.20%) | (3.50%) | (0.60%)
Foreign earnings taxed at different rates than U.S. | (0.30%) | (3.30%) | 11.80%
Valuation allowance | (4.30%) | 72.80% | 81.20%
Transition tax | 0 | 0 | (0.138)
Foreign restructuring | (2.30%) | 0.00% | 0.00%
Foreign dividends | (1.50%) | 0.00% | 0.00%
Net operating loss expiration and remeasurement | (10.80%) | (66.20%) | (75.80%)
Changes in uncertain tax reserves | 1.40% | 1.20% | (1.40%)
Other | 0.60% | 1.00% | 0.10%
Effective tax rate | 2.40% | 9.80% | 0.30%

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- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 + Details
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- Definition Percentage of domestic federal statutory tax rate applicable to pretax income (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.4) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 + Details
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- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.4) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 + Details
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- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.4) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 + Details
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