Financial instruments and fair value measurement Available-for-Sale Investments - Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016
Available-for-Sale Investments - Contractual Maturity [Abstract]
Less than one year, Amortized Cost	$ 15,993	$ 29,960
Less than one year, Fair Value	16,013	29,990
One to three years, Amortized Cost	152,602	144,100
One to three years, Fair Value	153,095	144,625
Above three years, Amortized Cost	54,167	34,276
Above three years, Fair Value	$ 54,419	$ 34,275