Taxes - Reconciliation of the United States Federal Statutory Corporate Tax Rate to Company's Effective Tax Rate or Income Tax Provision (Details)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense at U.S. federal statutory corporate tax rate	21.00%	35.00%	35.00%
State income taxes, net of federal benefit	1.00%	0.00%	1.00%
Foreign tax rate differential	(9.00%)	(27.00%)	(17.00%)
Tax credit	(0.00%)	(1.00%)	(1.00%)
Discrete tax benefit related to employee stock option exercises	(4.00%)	(14.00%)	(7.00%)
Discrete tax expense (benefit) related to 2017 Tax Act	(3.00%)	36.00%	0.00%
Discrete tax expense related to write-down of deferred tax assets	0.00%	5.00%	0.00%
Other discrete tax events	0.00%	(1.00%)	0.00%
Other	1.00%	1.00%	0.00%
Income tax expense on continuing operations	7.00%	34.00%	11.00%

Effective Income Tax Rate Reconciliation, Discrete Tax Expense, Percent

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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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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 applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Percentage of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to excess tax benefit for share-based compensation cost.

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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 tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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