Income Taxes (Details 3)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory federal tax rate	35.00%	35.00%	35.00%
Foreign rate differential	(10.70%)	(11.30%)	(7.80%)
Foreign, federal and state income tax credits	(2.00%)	(1.20%)	(2.10%)
State taxes	1.80%	2.30%	2.40%
Effective Income Tax Rate Reconciliation, Tax Settlement, Foreign, Percent	0.10%	14.40%	0.00%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent	0.00%	0.00%	(6.40%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	5.10%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent	23.80%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent	5.40%	0.00%	0.00%
Other	3.10%	0.40%	(0.20%)
Effective tax rate	61.60%	39.60%	20.90%