Summary of business and significant accounting policies - Description of Business, Revenue Recognition and Foreign Currency (Details)	12 Months Ended
	Jun. 30, 2019 USD ($) segment	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reporting segments | segment	3
Revenue, performance obligation, description of timing	we recognize revenue ratably over the period the services obligation is expected to be fulfilled, generally 8 to 12 years
Contract assets	$ 0	$ 0
Foreign currency transaction gains (losses)	$ (215,000)	$ 254,000	$ 318,000