Cash, cash equivalents and short-term investments - Summary of Fair Value and Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2019 USD ($) security	Jun. 30, 2019 USD ($) security
Fair Value
Less than 12 Months	$ 15,300	$ 5,093
12 Months or Greater	1,117	22,142
Total	16,417	27,235
Unrealized Losses
Less than 12 Months	(22)	(4)
12 Months or Greater	(2)	(41)
Total	$ (24)	$ (45)
Number of Positions
Less than 12 Months (securities) | security	45	11
12 Months or Greater (securities) | security	5	51
U.S. treasury securities
Fair Value
Less than 12 Months		$ 0
12 Months or Greater		2,992
Total		2,992
Unrealized Losses
Less than 12 Months		0
12 Months or Greater		(5)
Total		(5)
U.S. agency securities
Fair Value
Less than 12 Months	$ 2,032	0
12 Months or Greater	0	998
Total	2,032	998
Unrealized Losses
Less than 12 Months	(2)	0
12 Months or Greater	0	(1)
Total	(2)	(1)
Asset-backed securities
Fair Value
Less than 12 Months	7,308	0
12 Months or Greater	1,117	3,537
Total	8,425	3,537
Unrealized Losses
Less than 12 Months	(17)	0
12 Months or Greater	(2)	(11)
Total	(19)	(11)
Commercial paper
Fair Value
Less than 12 Months		493
12 Months or Greater		0
Total		493
Unrealized Losses
Less than 12 Months		(1)
12 Months or Greater		0
Total		(1)
Corporate bonds
Fair Value
Less than 12 Months	5,960	4,600
12 Months or Greater	0	14,615
Total	5,960	19,215
Unrealized Losses
Less than 12 Months	(3)	(3)
12 Months or Greater	0	(24)
Total	$ (3)	$ (27)