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Income Taxes - Reconciliation of statutory to effective income tax rate (Details)	12 Months Ended
	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

Effective Income Tax Rate Reconciliation, Foreign Dividends, Percentage

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Effective Income Tax Rate Reconciliation, Foreign Restructuring, Percentage

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Publisher FASB
-Name Accounting Standards Codification
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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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.

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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 income tax rates.

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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 state and local income tax expense (benefit), net of federal tax expense (benefit).

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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 income tax contingencies. Includes, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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Percentage of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to increase (decrease) from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act.

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