Annual report pursuant to Section 13 and 15(d)

Marketable Securities - Additional Information (Details)

v3.10.0.1
Marketable Securities - Additional Information (Details) - USD ($)
$ in Millions
12 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2016
Marketable Securities      
Realized gains on available-for-sale securities $ 0.2 $ 0.4 $ 0.9
Corporate and Government Securities      
Marketable Securities      
Investment portfolio, maximum maturity term 3 years