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Fair Value Disclosure - Summary of investments (Details) - Auction rate security - USD ($)
$ in Thousands
Mar. 31, 2019
Jun. 30, 2018
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]    
Cost Basis   $ 1,750
Gross Unrealized Holding Gains   0
Gross Unrealized Holding Losses   179
Fair Value   1,571
Fair Value, Measurements, Recurring    
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]    
Cost Basis $ 1,750  
Gross Unrealized Holding Gains 0  
Gross Unrealized Holding Losses (179)  
Fair Value 1,571  
Fair Value $ 1,571 $ 1,571