Stockholders' equity - Summary of Shares Available for Grant Activity (Details) - shares	5 Months Ended	7 Months Ended	12 Months Ended
	Nov. 20, 2019	Jun. 30, 2020	Jun. 30, 2020	Nov. 30, 2019
Summary of Shares Available for Grant [Roll Forward]
Shares available for grant at beginning period (in shares)	4,472,000		4,472,000
Shares available for grant at period end (in shares)		5,280,000	5,280,000
Equity Incentive Plan 2009 and 2011
Summary of Shares Available for Grant [Roll Forward]
Shares available for grant at beginning period (in shares)		0
Annual share increase authorized under 2009 Plan (in shares)	1,667,000
Granted (in shares)	(1,681,000)
RSUs withheld for taxes in net share settlements (in shares)	251,000
Canceled (in shares)	633,000
Expired under 2009 and 2011 Plans (in shares)	(5,342,000)
Shares available for grant at period end (in shares)	0
2019 Plan
Summary of Shares Available for Grant [Roll Forward]
Annual share increase authorized under 2009 Plan (in shares)		613,000
Initial shares authorized under 2019 Plan on November 20, 2019 (in shares)		5,700,000
Granted (in shares)		(1,068,000)
RSUs withheld for taxes in net share settlements (in shares)		35,000
Additional capital shares reserved for future issuance (in shares)		5,800,000,000	5,800,000,000	5,800,000