Income Taxes - Reconciliation of Effective Income Taxes Rate (Details 6)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of effective income taxes rate
Taxes at the U.S. statutory rate	35.00%	35.00%	35.00%
State income taxes, net of federal income tax benefit	1.10%	1.40%	(0.10%)
Non-U.S. income taxed at rates different than the U.S. statutory rate	(9.00%)	(7.50%)	(16.70%)
Foreign source income, net of associated foreign tax credits	0.10%	5.30%	6.90%
Benefit of tax credits	(1.40%)	(1.00%)	(4.60%)
Non-deductible expenses	1.50%	0.70%	1.30%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent	(1.50%)	(0.80%)	0.00%
Adjustment to valuation allowances	(4.40%)	3.80%	37.80%
Benefit from prior period foreign tax credits	(0.00%)	(0.00%)	(133.00%)
Change in unrecognized tax benefits	2.00%	3.30%	59.50%
Impacts of unremitted foreign earnings	0.90%	0.60%	60.80%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent	44.70%	0.00%	0.00%
Other	(4.90%)	(0.90%)	(3.60%)
Effective income tax rate	64.10%	39.90%	43.30%