Financial instruments and fair value measurement Available-for-Sale Investments - Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Jun. 30, 2016
Available-for-Sale Investments - Contractual Maturity [Abstract]
Less than one year, Amortized Cost	$ 15,784	$ 29,960
Less than one year, Fair Value	15,785	29,990
One to three years, Amortized Cost	148,806	144,100
One to three years, Fair Value	149,105	144,625
Above three years, Amortized Cost	43,745	34,276
Above three years, Fair Value	$ 43,790	$ 34,275