Summary of business and significant accounting policies - Goodwill (Details) $ in Thousands	12 Months Ended
	Jun. 30, 2019 USD ($) reporting_unit	Jun. 30, 2018 USD ($)		Jun. 30, 2017 USD ($)	[1]
Goodwill [Line Items]
Number of reporting units | reporting_unit	3
Impairment	$ 2,556	$ 2,666	[1]	$ 0
Goodwill	26,106	28,662
Advertising Segment
Goodwill [Line Items]
Impairment	2,556
Goodwill	$ 11,786	14,342
Mobile Navigation
Goodwill [Line Items]
Impairment		$ 2,700

[1] See Note 1 for a summary of adjustments.