Financial instruments - Gain (Losses) on Derivative Financial Instruments (Details) - Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended
Sep. 30, 2017	Sep. 30, 2016
Cross-currency swap contracts
Derivative Instruments, Gain (Loss)
Derivative and non derivative instruments gain (loss) recognized in accumulated other comprehensive income (loss)	$ (6,574)	$ (6,241)
Foreign denominated debt
Derivative Instruments, Gain (Loss)
Derivative and non derivative instruments gain (loss) recognized in accumulated other comprehensive income (loss)	$ (16,834)	$ (673)

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.

Name:	us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration