Stockholders' equity - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 9,876	$ 10,162	$ 11,366
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	145	130	143
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	5,535	5,543	6,062
Selling and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,671	2,090	2,844
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,525	2,399	2,317
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,103	2,384	1,893
Restricted stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 7,773	$ 7,778	$ 9,473