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Collaborative Arrangement, Success-Based Payments, Amount

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Percentage of sharing in development costs.

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Percentage of sharing in Phase 2 development costs.

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Percentage of sharing in production costs.

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Potential development and regulatory milestones.

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Potential development milestones.

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Reimbursement of expenses.

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Sale of stock consideration received.

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Upfront and milestone payments received from license agreements.

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Upfront and milestone payments received under license agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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License and Collaboration Agreements - Additional Information (Details) - USD ($)				1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 12, 2021	Feb. 13, 2018	Jul. 23, 2017	Apr. 30, 2018	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Derivative liability						$ 0
Revenue, excluding assessed tax					$ 21,594,000	24,822,000
SFJ
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Committed funding (up to)	$ 150,000,000
Success payments (up to)	$ 637,500,000
Bristol Myers Squibb Company \| Purchase Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Shares issued (in shares)				8,284,600
Sale of stock consideration received				$ 850,000,000
Other Partner
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future additional payments for development milestones (up to)					40,000,000
Nektar-358 \| Nektar's
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Received upfront and milestone payment			$ 150,000,000
Percentage of sharing in Phase 2 development costs			25.00%
Nektar-358 \| Eli Lilly And Company \| Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future additional development and regulatory milestones (up to)			$ 250,000,000
Nektar-358 \| Eli Lilly
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing in Phase 2 development costs			75.00%
Nektar 214 \| Bristol Myers Squibb Company \| Research and Development Expense
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of expenses							$ 24,900,000
Nektar 214 \| Bristol Myers Squibb Collaboration Agreement \| Nektar's
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing production costs		65.00%
Upfront and milestone payments received from license agreements				$ 1,000,000,000
Nektar 214 \| Bristol Myers Squibb Collaboration Agreement \| Nektar's \| Milestone One
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future additional payments for development milestones (up to)								$ 50,000,000
Nektar 214 \| Bristol Myers Squibb Collaboration Agreement \| Bristol Myers Squibb Company
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing production costs		35.00%
Nektar 214 \| Opdivo \| Bristol Myers Squibb Collaboration Agreement \| Nektar's
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing development costs		32.50%
Nektar 214 \| Opdivo \| Bristol Myers Squibb Collaboration Agreement \| Bristol Myers Squibb Company
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing development costs		67.50%
Non-cash royalty revenue related to the sales of future royalties
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue, excluding assessed tax					$ 16,861,000	$ 17,561,000