Marketable Securities - Fair Value, Amortized Cost and Unrealized Holding Gains (Losses) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Jun. 30, 2015
Short-term Marketable Securities
Marketable Securities
Fair Value	$ 29,946	$ 59,197
Cost	29,967	59,223
Unrealized Gain	1	8
Unrealized Loss	(22)	(34)
Long-term Marketable Securities
Marketable Securities
Fair Value	0	3,047
Cost	0	3,055
Unrealized Gain	0	0
Unrealized Loss	0	(8)
U.S. corporate bonds | Short-term Marketable Securities
Marketable Securities
Fair Value	29,946	59,197
Cost	29,967	59,223
Unrealized Gain	1	8
Unrealized Loss	(22)	(34)
U.S. corporate bonds | Long-term Marketable Securities
Marketable Securities
Fair Value	0	3,047
Cost	0	3,055
Unrealized Gain	0	0
Unrealized Loss	$ 0	$ (8)