Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
U.S. federal statutory income tax rate	21.00%	35.00%	35.00%
State income taxes, net of federal benefit	0.70%	0.60%	1.00%
Research tax credits	(1.00%)	(0.90%)	(0.70%)
Share-based compensation	0.30%	0.40%	1.00%
Excess tax benefits related to share-based compensation	(2.60%)	(5.80%)	(7.00%)
Effect of non-U.S. operations	(5.90%)	(18.60%)	(12.80%)
Effect of U.S. tax law change	0.00%	11.00%	0.00%
Other	0.30%	0.90%	1.90%
Effective tax rate	12.80%	22.60%	18.40%

Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act of 2017, Percent

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Effective Tax Rate Reconciliation, Share-Based Compensation, Excess Tax Benefit, 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 applicable to statutory income tax expense (benefit) outside of the country of domicile.

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