Financial instruments and fair value measurement Available-for-Sale Investments - Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Jun. 30, 2015
Available-for-Sale Investments - Contractual Maturity [Abstract]
Less than one year, Amortized Cost	$ 14,141	$ 13,561
Less than one year, Fair Value	14,141	13,555
One to three years, Amortized Cost	184,281	188,539
One to three years, Fair Value	184,115	188,057
Above three years, Amortized Cost	11,696	15,673
Above three years, Fair Value	$ 11,598	$ 15,587