Taxes on Income, Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Company's provision for taxes on income varied from the statutory federal income tax rate [Abstract]
United States income tax statutory rate	35.00%	35.00%	35.00%
State and local taxes, net of federal benefit	0.90%	1.80%	1.70%
Change due to U.S. tax reform	(369.00%)	0.00%	0.00%
Other - net	3.20%	0.50%	0.30%
Effective income tax rate	(329.90%)	37.30%	37.00%