Stockholders' equity - Narrative - Stock Plans and Performance-based RSUs (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2018 milestone shares	Dec. 31, 2016 shares	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 USD ($)		Jun. 30, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period			10 years
Cash received from exercises of stock options | $			$ 8,853	$ 681	[1]	$ 2,738	[1]
Total intrinsic value of stock options exercised | $			$ 1,100	227		6,100
Granted (in shares)			1,485,000
Total unrecognized stock-based compensation cost related to options | $			$ 1,300
Total fair value of stock options vested | $			$ 3,700	2,400		2,200
Stock option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Period for recognition of unrecognized stock-based compensation cost			1 year 9 months 7 days
Nonqualified stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant price of options as percentage of fair market value on the date of grant			85.00%
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Number of shares canceled (in shares)			475,000
Period for recognition of unrecognized stock-based compensation cost			2 years 3 months 3 days
Total unrecognized stock-based compensation cost related to RSU's | $			$ 8,500
Total fair value of restricted stock units vested | $			$ 6,000	$ 7,000		8,200
Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Number of performance milestones | milestone	4
Trading days, period	50 days
Number of shares canceled (in shares)		70,000
2009 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for and reserved for issuance annual increment amount (in shares)			1,666,666
Annual increase to shares reserved for future issuance as percentage of total outstanding shares			4.00%
2015 Performance Share Program | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation not yet recognized | $						$ 546,000
Maximum | 2015 Performance Share Program | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	240,000
Vesting tranche one | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares eligible to vest (in shares)	0.25
Vesting tranche two | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares eligible to vest (in shares)	0.50
Vesting tranche three | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares eligible to vest (in shares)	0.50

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