Summary of business and significant accounting policies - Accumulated Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	$ 90,640	$ 108,883	$ 141,704
Other comprehensive income (loss) before reclassifications, net of tax	1,059	355
Amount reclassified from accumulated other comprehensive income (loss), net of tax	(59)	23
Other comprehensive income, net of tax	1,000	378	79
Balance	96,970	90,640	108,883
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(1,477)	(1,855)	(1,934)
Balance	(477)	(1,477)	(1,855)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(1,623)	(1,162)
Other comprehensive income (loss) before reclassifications, net of tax	(211)	(461)
Amount reclassified from accumulated other comprehensive income (loss), net of tax	0	0
Other comprehensive income, net of tax	(211)	(461)
Balance	(1,834)	(1,623)	(1,162)
Unrealized Gains (Losses) on Available- for-Sale Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	146	(693)
Other comprehensive income (loss) before reclassifications, net of tax	1,270	816
Amount reclassified from accumulated other comprehensive income (loss), net of tax	(59)	23
Other comprehensive income, net of tax	1,211	839
Balance	$ 1,357	$ 146	$ (693)