Summary of business and significant accounting policies - Deferred Costs (Details) $ in Thousands	6 Months Ended
	Dec. 31, 2019 USD ($)
Contract with Customer Asset [Roll Forward]
Balance, June 30, 2019	$ 79,802
Content licensing costs incurred	64,612
Customized software development costs incurred	2,503
Less: cost of revenue recognized	(65,154)
Balance, December 31, 2019	81,763
Content
Contract with Customer Asset [Roll Forward]
Balance, June 30, 2019	71,466
Content licensing costs incurred	64,612
Customized software development costs incurred	0
Less: cost of revenue recognized	(62,785)
Balance, December 31, 2019	73,293
Development
Contract with Customer Asset [Roll Forward]
Balance, June 30, 2019	8,336
Content licensing costs incurred	0
Customized software development costs incurred	2,503
Less: cost of revenue recognized	(2,369)
Balance, December 31, 2019	$ 8,470