Reverse Recapitalization - Schedule of Reverse Recapitalization - Reconciliation Elements of The Business Combination to the Company’s Unaudited Condensed Consolidated Financial Statements (Details) - USD ($) $ in Thousands		6 Months Ended
	Sep. 29, 2023	Jun. 30, 2024	Jun. 30, 2023
Schedule Of Reverse Recapitalization [Line Items]
Proceeds from issuance of common stock	$ 1,667	$ 873	$ 0
Proceeds from amendment to the PIPE warrants	10,210	250	0
Proceeds from issuance of senior convertible promissory notes with warrants	10,000
Less: Payment of Graf deferred underwriter fees	(1,250)
Payment of transaction costs		(40)	(1,742)
Net cash proceeds from the Business Combination at Closing	9,661
Less: Payment of Legacy NKGen transaction costs prior to Closing	(2,089)
Net cash proceeds from the Business Combination	7,572
Conversion of legacy NKGen convertible promissory notes	18,913	$ 12	$ 0
Less: Operating liabilities assumed from Graf	(860)
Less: Fair value of PIPE warrants	(10,210)
Less: Fair value of forward purchase derivative liabilities	(20,201)
Less: Fair value of senior convertible promissory notes	(9,707)
Less: Fair value of private warrants	(1,841)
Less: Fair value of working capital warrants	(204)
Net equity impact of the Business Combination	(23,876)
Graf Acquisition Partners IV LLC
Schedule Of Reverse Recapitalization [Line Items]
Payment of transaction costs	(7,456)
Less: Unpaid transaction costs	(5,400)
Legacy NKGen
Schedule Of Reverse Recapitalization [Line Items]
Payment of transaction costs	(3,510)
Less: Unpaid transaction costs	$ (1,938)