Derivative instruments and hedging activities (Tables)

3 Months Ended

Mar. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of balance sheet classification and fair values of derivative instruments

The following table summarizes the consolidated balance sheets classification and fair values of the Company’s derivative instruments:

		Fair Value						Notional Amount
		March 31,			December 31,			March 31,		December 31,
	Balance sheet location	2018			2017			2018		2017
					U. S. $ in thousands
Assets derivatives -Foreign exchange contracts, not designated as hedging instruments	Other current assets	$	121		$	90		$	35,453	$	22,036
Assets derivatives -Foreign exchange contracts, designated as cash flow hedge	Other current assets		24			263			7,788		13,169
Liability derivatives -Foreign exchange contracts, not designated as hedging instruments	Accrued expenses and other current liabilities		(1,103	)		(921	)		48,018		65,668
Liability derivatives -Foreign exchange contracts, designated as hedging instruments	Accrued expenses and other current liabilities		(20	)		-			8,460		-
		$	(978	)	$	(568	)	$	99,719	$	100,873