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The Company and Summary of Significant Accounting Policies - Additional Information (Detail) | 6 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jun. 30, 2019 USD ($) | Jun. 30, 2020 USD ($) ClinicalTrials shares | Jun. 30, 2019 USD ($) shares | Jun. 30, 2018 USD ($) shares | Jun. 30, 2017 | May 31, 2020 USD ($)
Targeted or Tracking Stock, Stock [Line Items] |  |  |  |  |  |
Number of clinical stage candidates | ClinicalTrials |  | 4 |  |  |  |
Number of candidate in an ongoing global registration trial | ClinicalTrials |  | 1 |  |  |  |
Short-term investments | $ 64,899,000 | $ 170,299,000 | $ 64,899,000 |  |  |
Estimated life of the intellectual property |  | 14 years |  |  |  |
Corporate tax rate | 21.00% | 21.00% | 21.00% | 28.00% | 34.00% |
Non-Cash Tax Expense |  | $ 0 | $ 0 | $ 15,870,000 |  |
Deferred Revenue Associated With Remaining Performance Obligation |  | 82,500,000 |  |  |  |
Unrecognized tax benefits | $ 0 | 0 | 0 |  |  |
Recognition Of Deferred Revenue |  | 14,800,000 |  |  |  |
Additional Recognition Of Deferred Revenue |  | 67,700,000 |  |  |  |
Revenue Recognised With Performance Obligation |  | $ 6,600,000 | $ 1,700,000 |  |  |
Common stock subject to repurchase or forfeiture | shares |  | 0 | 0 | 0 |  |
Accumulated Losses Since Inception | (231,218,000) | $ (277,234,000) | $ (231,218,000) |  |  |
Cash And Cash Equivalents,Short Term Investments And Common Stock Proceeds Receivable |  | $ 182,600,000 |  |  |  |
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. |  |  |  |
Impairment of finite lived intangible assets |  | $ 227,000 |  |  |  |
Effective Income Tax Rate Reconciliation, Deduction, Percent |  | 80.00% |  |  |  |
Helsinn License Agreement |  |  |  |  |  |
Targeted or Tracking Stock, Stock [Line Items] |  |  |  |  |  |
Deferred Revenue Associated With Remaining Performance Obligation | $ 2,300,000 | $ 1,400,000 | 2,300,000 |  |  |
KKC Agreements and Helsinn License Agreement [Member] |  |  |  |  |  |
Targeted or Tracking Stock, Stock [Line Items] |  |  |  |  |  |
Contract with Customer, Liability, Revenue Recognized |  | 7,800,000 | 800,000 | $ 1,000,000 |  |
S*Bio Patents |  |  |  |  |  |
Targeted or Tracking Stock, Stock [Line Items] |  |  |  |  |  |
Impairment of finite lived intangible assets |  | $ 200,000 |  |  |  |
Minimum [Member] |  |  |  |  |  |
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 |  |  |  |
KHK License Agreement |  |  |  |  |  |
Targeted or Tracking Stock, Stock [Line Items] |  |  |  |  |  |
Revenue Recognised With Performance Obligation |  | $ 21,000,000 | $ 900,000 |  |  |
Termination Of KKC Japan License Agreement And Execution Of KKC License Agreement |  |  |  |  |  |
Targeted or Tracking Stock, Stock [Line Items] |  |  |  |  |  |
Performance obligation cumulative catch up adjustment |  | 3,100,000 |  |  |  |
Kyowa Kirin Co |  |  |  |  |  |
Targeted or Tracking Stock, Stock [Line Items] |  |  |  |  |  |
Milestone payment receivable current |  | 20,400,000 |  |  |  |
Total upfront payment receivable for grant of rights |  | 100,000,000 |  |  |  | $ 100,000,000
Kyowa Kirin Co | Potential Payments on Achievement of Development Regulatory and Commercial Milestones [Member] |  |  |  |  |  |
Targeted or Tracking Stock, Stock [Line Items] |  |  |  |  |  |
Total upfront payment receivable for grant of rights |  | $ 100,000,000 |  |  |  |

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