Convertible Notes - Legacy Convertible Notes (Details) - USD ($) $ in Thousands		47 Months Ended
	Sep. 29, 2023	Sep. 30, 2023	Dec. 31, 2019
Debt Instrument [Line Items]
Proceeds from convertible debt	$ 10,000
Convertible Debt | Legacy Convertible Notes
Debt Instrument [Line Items]
Proceeds from convertible debt		$ 17,300
Interest rate		4.60%	1.70%
Convertible Debt | Legacy Convertible Notes | Legacy NKGen Common Stock
Debt Instrument [Line Items]
Issuance of common stock in connection with financial instrument transactions (in shares)	5,579,266
Convertible Debt | Legacy Convertible Notes | Common Stock
Debt Instrument [Line Items]
Issuance of common stock in connection with financial instrument transactions (in shares)	2,278,598
Convertible Debt | Legacy Convertible Notes | Related party
Debt Instrument [Line Items]
Proceeds from convertible debt		$ 400