Taxes on Income - Deferred Tax Assets and Liabilities in Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Current deferred income tax assets, net (1)	$ 0	$ 7,824
Current deferred income tax liabilities, net	0	(3,317)
Noncurrent deferred income tax assets, net	1,666	1,848
Noncurrent deferred income tax liabilities, net	(9,211)	(23,339)
Net deferred income tax liabilities	$ (7,545)	$ (16,984)