Financial Instruments Available-for-Sale Investments - Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Jun. 30, 2015
Available-for-sale Securities, Debt Maturities [Abstract]
Less than one year, amortized cost	$ 29,960	$ 13,561
Less than one year, fair value	29,990	13,555
One to three years, amortized cost	144,100	188,539
One to three years, fair value	144,625	188,057
Over three years, amortized cost	34,276	15,673
Over three years, fair value	$ 34,275	$ 15,587