Derivative instruments and hedging activities (Narrative) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
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Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
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| Derivatives, Fair Value [Line Items] | ||||
| Notional amount of derivative asset | $ 85.6 | $ 85.6 | ||
| Gain (Loss) on derivative instrument | 3.3 | $ (2.4) | 1.0 | $ (2.7) |
| Other current assets [Member] | Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Conversion To NIS [Member] | ||||
| Derivatives, Fair Value [Line Items] | ||||
| Notional amount of derivative asset | $ 23.5 | $ 23.5 | ||
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- Definition Nominal or face amount used to calculate payments on the derivative asset. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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