Income Taxes - Reconciliation of Effective Income Taxes Rate (Details 6)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of effective income taxes rate
Taxes at the U.S. statutory rate	21.00%	35.00%	35.00%
State income taxes, net of federal income tax benefit	1.20%	1.10%	1.40%
Non-U.S. income taxed at rates different than the U.S. statutory rate	0.80%	(9.00%)	(7.50%)
Foreign source income, net of associated foreign tax credits	4.10%	0.10%	5.30%
Benefit of tax credits	(0.90%)	(1.40%)	(1.00%)
Non-deductible expenses	1.30%	1.50%	0.70%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent	(0.90%)	(1.50%)	(0.80%)
Adjustment to valuation allowances	(0.60%)	(4.40%)	3.80%
Other changes in tax laws and rates	(6.10%)	(0.00%)	(0.00%)
Change in unrecognized tax benefits	(1.70%)	2.00%	3.30%
Impacts of unremitted foreign earnings	1.10%	0.90%	0.60%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent	(0.60%)	44.70%	0.00%
Other	1.20%	(4.90%)	(0.90%)
Effective income tax rate	19.90%	64.10%	39.90%