Additional tenant improvement allowances.

No definition available.

Name:	nktx_AdditionalTenantImprovementAllowances
Namespace Prefix:	nktx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Lease expiration month and year.

+ References

No definition available.

+ Details

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Namespace Prefix:	nktx_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Lease expiration year.

+ References

No definition available.

+ Details

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Namespace Prefix:	nktx_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Tenant improvement costs equal monthly payments annual rate.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Description of lessee's operating lease.

+ References

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicates (true false) whether lessee has option to extend operating lease.

+ References

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- Definition

Description of terms and conditions of option to extend lessee's operating lease. Includes, but is not limited to, information about option recognized as part of right-of-use asset and lease liability.

+ References

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- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

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Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

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Balance Type:	na
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- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

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Balance Type:	debit
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- Definition

Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Weighted average discount rate for operating lease calculated at point in time.

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Balance Type:	na
Period Type:	instant

- Definition

Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Amount of sublease income excluding finance and operating lease expense.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Period Type:

- Details

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Period Type:

- Details

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Leases - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended					3 Months Ended		6 Months Ended
	Jun. 30, 2023	Oct. 31, 2021	Jan. 31, 2021	May 31, 2020	May 31, 2018	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Jul. 31, 2021
Lessee Lease Description [Line Items]
Rent expense						$ 2.4	$ 2.6	$ 4.8	$ 5.3
Weighted-average remaining lease term						8 years 7 months 6 days		8 years 7 months 6 days
Cash paid for operating leases								$ 5.6	$ 7.6
Weighted-average discount rate						9.70%		9.70%
Lessee, operating lease, term of contract										12 years
Additional tenant improvement allowances	$ 4.4
Sublease income								$ 0.0
Tenant improvement costs in equal monthly payments annual rate	8.50%
Third amendment
Lessee Lease Description [Line Items]
Operating lease, description								The lease amendment for this additional space commenced in April 2021 and expired in March 2024.
Lease expiration month and year			2024-03
Initial Lease Agreement
Lessee Lease Description [Line Items]
Lease expiration year					2025
Operating lease, existence of option to extend		true		true
Corporate Office and Laboratory Space \| Initial Lease Agreement
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend					true
Lessee option to extend description								In April 2019, the Company executed the first amendment to the Initial Lease Agreement for additional corporate space, laboratory space and manufacturing capabilities.
Renewal term					7 years