The Company and Summary of Significant Accounting Policies - Additional Information (Detail) shares in Thousands, $ in Thousands	12 Months Ended
	Jun. 30, 2021 USD ($) Trails shares	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($) shares
Targeted or Tracking Stock, Stock [Line Items]
Number of clinical stage candidates | Trails	4
Short-term investments	$ 144,883	$ 170,299
Deferred Revenue, Revenue Recognized	79,200
Unrecognized tax benefits	0	0
Revenue Recognised With Performance Obligation	$ 34,400	$ 26,400	$ 2,600
Common stock subject to repurchase or forfeiture | shares	0	0	0
Accumulated Losses Since Inception	$ (319,705)	$ (278,391)
Cash And Cash Equivalents,Short Term Investments And Common Stock Proceeds Receivable	153,400
Unbilled receivables, Current	$ 7,582	2,858	$ 511
Percentage of reimbursement of pass through costs as revenue	100.00%
Changes in unrecognized tax position	An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained.
Ex US License
Targeted or Tracking Stock, Stock [Line Items]
Deferred Revenue, Revenue Recognized	$ 14,700
US License
Targeted or Tracking Stock, Stock [Line Items]
Deferred Revenue, Revenue Recognized	64,500
Helsinn License Agreement
Targeted or Tracking Stock, Stock [Line Items]
Deferred Revenue, Revenue Recognized	400	$ 1,400	$ 2,300
KKC Commercialization Agreement And The Helsinn License Agreement
Targeted or Tracking Stock, Stock [Line Items]
Unbilled receivables, Current	$ 7,600
Minimum
Targeted or Tracking Stock, Stock [Line Items]
Property and equipment, estimated useful life	3 years
Maximum
Targeted or Tracking Stock, Stock [Line Items]
Property and equipment, estimated useful life	7 years