Cash, restricted cash, cash equivalents, and available for sale investments.

No definition available.

Name:	nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Organization and summary of significant accounting policies.

+ References

No definition available.

+ Details

Name:	nktr_OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix:	nktr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of expense (reversal of expense) for expected credit loss on accounts receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

+ Details

Name:	us-gaap_ProvisionForDoubtfulAccounts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of positions eliminated during the period as a percentage of total positions eliminated during the period in connection with the restructuring plan(s).

+ References

No definition available.

+ Details

Name:	us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RestructuringCostAndReserveAxis=us-gaap_EmployeeSeveranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RestructuringPlanAxis=nktr_TwoThousandTwentyTwoRestructuringPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RestructuringPlanAxis=nktr_TwoThousandTwentyThreeRestructuringPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	Jun. 30, 2023	Apr. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Organization And Summary Of Significant Accounting Policies [Line Items]
Cash and investments in marketable securities			$ 372,658,000		$ 372,658,000		$ 504,977,000
Accounts receivable, credit loss expense (reversal)			$ 0	$ 0	$ 0	$ 0
Employee Severance \| 2022 Restructuring Plan
Organization And Summary Of Significant Accounting Policies [Line Items]
Workforce termination, percentage		70.00%
Employee Severance \| 2023 Restructuring Plan
Organization And Summary Of Significant Accounting Policies [Line Items]
Workforce termination, percentage	60.00%