Income Taxes (Details 1)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of federal statutory tax rate with effective tax rate
Federal statutory tax rate	35.00%	35.00%	35.00%
Impact of one-time deemed repatriation	10.70%	0.00%	0.00%
Impact on deferred taxes for changes in tax rates	(197.50%)	(0.70%)	(0.90%)
State income taxes, net of federal income tax benefit	4.50%	5.00%	5.00%
Foreign rates varying from federal statutory tax rate	(4.00%)	(3.30%)	(3.30%)
Tax reviews and audits	(1.00%)	(0.70%)	(1.30%)
Other, net	0.20%	(0.40%)	0.30%
Effective tax rate	(152.10%)	34.90%	34.80%