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Development regulatory and sales milestones payments.

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Expected payments of leasehold improvements, net of tenant improvement allowances.

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Lease commencement month and year.

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Ratio of profit sharing structure for commercialization.

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Area of land subject to a ground lease.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
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Subsequent Events - Additional Information (Detail)	Oct. 23, 2020 USD ($) ft²	Oct. 07, 2020 USD ($)	Sep. 30, 2019 USD ($)
Subsequent Event [Line Items]
Estimated lease payments			$ 22,385,552
Subsequent Event \| Corporate Headquarters In Pasadena \| California
Subsequent Event [Line Items]
Office space leases, in square feet \| ft²	24,434
Lease commencement period	2021-07
Lease expiration month and year	2027-04
Estimated lease payments	$ 7,300,000
Expected leasehold improvements, net of tenant improvement allowances	$ 4,000,000.0
Takeda License Agreement \| License and Co-Funding Agreement \| Subsequent Event
Subsequent Event [Line Items]
Agreement date		Oct. 07, 2020
Ratio of Profit Sharing Structure for United States Commercialization		50/50 profit sharing
Cash received as due under collaboration agreement		$ 300,000,000.0
Development regulatory and sales milestones payments		$ 740,000,000.0
Takeda License Agreement \| Minimum \| License and Co-Funding Agreement \| Subsequent Event
Subsequent Event [Line Items]
Percentage of eligible to receive tiered royalties on net sales		20.00%
Takeda License Agreement \| Maximum \| License and Co-Funding Agreement \| Subsequent Event
Subsequent Event [Line Items]
Percentage of eligible to receive tiered royalties on net sales		25.00%
Development regulatory and sales milestones payments		$ 740,000,000.0