Percentage of development milestones payments, to be received, if conditions occur.

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Percentage of development milestones payments, to be received under certain conditions.

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Percentage of funding Phase three development costs on an indication by indication basis borne.

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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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Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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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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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			6 Months Ended
	Feb. 13, 2018	Jul. 23, 2017	Apr. 30, 2018	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable				$ 10,006,000			$ 10,006,000		$ 22,492,000
Revenue, excluding assessed tax				21,585,000		$ 28,330,000	46,407,000	$ 51,977,000
Bristol Myers Squibb Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable				7,400,000			7,400,000		$ 21,400,000
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			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 And Company \| Nektar's
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of regulatory milestones payments will be reduced under certain conditions		50.00%
Percentage of regulatory milestones payments will be reduced if conditions occur		75.00%
Nektar-358 \| Eli Lilly And Company \| Nektar's \| Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of funding phase 3 development costs on an indication by indication basis borne		25.00%
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				7,600,000	$ 24,900,000	24,800,000	7,600,000	51,400,000
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				$ 16,264,000		$ 20,456,000	$ 33,825,000	$ 39,254,000