Summary of business and significant accounting policies - Accumulated Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	$ 112,148	$ 149,685	$ 176,183
Other comprehensive income (loss) before reclassifications, net of tax	77	(172)
Amount reclassified from accumulated other comprehensive income (loss), net of tax	5	5
Other comprehensive income (loss), net of tax	82	(167)	(227)
Balance	31,046	112,148	149,685
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(1,934)	(1,767)	(1,540)
Balance	(1,852)	(1,934)	(1,767)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(1,701)	(1,889)
Other comprehensive income (loss) before reclassifications, net of tax	542	188
Amount reclassified from accumulated other comprehensive income (loss), net of tax	0	0
Other comprehensive income (loss), net of tax	542	188
Balance	(1,159)	(1,701)	(1,889)
Unrealized Gains (Losses) on Available- for-Sale Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(233)	122
Other comprehensive income (loss) before reclassifications, net of tax	(465)	(360)
Amount reclassified from accumulated other comprehensive income (loss), net of tax	5	5
Other comprehensive income (loss), net of tax	(460)	(355)
Balance	$ (693)	$ (233)	$ 122