Derivative instruments and hedging activities (Tables)

3 Months Ended

Mar. 31, 2015

Derivative instruments and hedging activities [Abstract]

Schedule of balance sheet classification and fair values of derivative instruments

		Fair Value						Notional Amount
		March 31,			December 31,			March 31,		December 31,
	Balance sheet location	2015			2014			2015		2014
		U.S. $ in thousands
Assets derivatives -Foreign exchange contracts,
not designated as hedging instruments	Other current assets	$	4,007		$	3,753		$	46,050	$	45,000
Liability derivatives -Foreign exchange contracts,	Accrued expenses and
not designated as hedging instruments	other current liabilities		(2,811	)		(2,901	)		12,686		18,424
Liability derivatives -Foreign exchange contracts,	Accrued expenses and
designated as cash flow hedge	other current liabilities		(863	)		(1,243	)		38,794		38,426
		$	333		$	(391	)	$	97,530	$	101,850