Summary of business and significant accounting policies - Deferred Costs (Details) $ in Thousands	12 Months Ended
	Jun. 30, 2019 USD ($)
Contract with Customer Asset [Roll Forward]
Balance, June 30, 2018	$ 58,425
Content licensing costs incurred	123,493
Customized software development costs incurred	2,537
Less: cost of revenue recognized	(104,653)
Balance, June 30, 2019	79,802
Content
Contract with Customer Asset [Roll Forward]
Balance, June 30, 2018	48,946
Content licensing costs incurred	123,493
Customized software development costs incurred	0
Less: cost of revenue recognized	(100,973)
Balance, June 30, 2019	71,466
Development
Contract with Customer Asset [Roll Forward]
Balance, June 30, 2018	9,479
Content licensing costs incurred	0
Customized software development costs incurred	2,537
Less: cost of revenue recognized	(3,680)
Balance, June 30, 2019	$ 8,336