Cash, cash equivalents and short-term investments - Summary of cost and estimated fair value of short-term investments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Jun. 30, 2019
Amortized Cost
Due within one year	$ 44,564
Due between one and two years	44,235
Due between two and three years	18,444
Amortized Cost	107,243	$ 70,493
Estimated Fair Value
Due within one year	44,549
Due between one and two years	44,345
Due between two and three years	18,379
Total	$ 107,273	$ 70,854