Fair Value of Financial Instruments - Narrative (Details) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended		47 Months Ended
	Sep. 29, 2023 USD ($) $ / shares shares	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) $ / shares	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Stock converted, reverse recapitalization (in shares) | shares	2,278,598
Conversion of legacy NKGen convertible promissory notes	$ 18,913		$ 12	$ 0
Stock converted, reverse recapitalization (in USD per share) | $ / shares	$ 8.30
Proceeds from convertible debt	$ 10,000
Loss on issuance of convertible notes			700
Total Forward Purchase Derivative Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liability			$ 10,511			$ 10,085	$ 15,804
Warrant, exercise price (in dollars per share) | $ / shares			$ 1.27
Convertible Bridge Loan Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liability			$ 840
Convertible Bridge Loan Warrants | Relative Fair Value At Initial Recognition
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liability			1,400
Convertible Bridge Loan Warrants | Residual Fair Value
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liability			$ 100
Dividend yield (per share)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Private warrants and working capital warrants unobservable input			0
Legacy Convertible Notes | Convertible Debt
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Proceeds from convertible debt					$ 17,300
Legacy Convertible Notes | Nonrelated Party
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expense associated with change in fair value		$ 1,300		2,800
Convertible Bridge Loans
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Proceeds from convertible debt			$ 700	$ 0
Convertible Bridge Loans | Convertible Debt
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Proceeds from convertible debt			$ 700