Short-Term Investments - Schedule of Short-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jun. 30, 2019
Schedule Of Available For Sale Securities [Line Items]
Short-term investments, Amortized cost	$ 68,095	$ 71,894
Short-term investments, Gross unrealized gains	46	75
Short-term investments, Gross unrealized losses	(6)
Short-term investments	68,135	71,969
U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Short-term investments, Amortized cost	42,648	64,683
Short-term investments, Gross unrealized gains	38	75
Short-term investments	42,686	64,758
Corporate Bonds
Schedule Of Available For Sale Securities [Line Items]
Short-term investments, Amortized cost	17,378	4,787
Short-term investments, Gross unrealized gains	7
Short-term investments, Gross unrealized losses	(3)
Short-term investments	17,382	4,787
Asset-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Short-term investments, Amortized cost	8,069	2,424
Short-term investments, Gross unrealized gains	1
Short-term investments, Gross unrealized losses	(3)
Short-term investments	$ 8,067	$ 2,424