Summary of business and significant accounting policies (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Total revenue	$ 52,168	$ 56,962	[1]
Product
Disaggregation of Revenue [Line Items]
Total revenue	40,471	42,659	[1]
Services
Disaggregation of Revenue [Line Items]
Total revenue	11,697	14,303	[1]
Point in Time | On-board automotive navigation solutions
Disaggregation of Revenue [Line Items]
Total revenue	40,471	42,659
Point in Time | Advertising services
Disaggregation of Revenue [Line Items]
Total revenue	5,947	7,615
Over Time | Brought-in automotive navigation solutions
Disaggregation of Revenue [Line Items]
Total revenue	2,980	2,949
Over Time | Mobile navigation services
Disaggregation of Revenue [Line Items]
Total revenue	$ 2,770	$ 3,739

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