Term Debt - Additional Information (Details) $ in Millions		1 Months Ended	6 Months Ended
Term Debt - Additional Information (Details) $ in Millions	Jul. 01, 2023	Feb. 28, 2022 USD ($) Months	Jun. 30, 2024 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Debt issuance costs			$ 1.2
Debt instrument final payment fee accrued			2.8
Capital stock in excess		$ 0.3
2022 Loan Agreement
Debt Instrument [Line Items]
Debt instrument maturity date		Feb. 01, 2027
Debt instrument basis spread on variable rate	7.83%
Debt instrument interest rate during period	0.10%
2022 Loan Agreement \| Oxford
Debt Instrument [Line Items]
Long-term debt		$ 60.0
Long-term debt		In February 2022, the Company entered into a new Loan and Security Agreement (“2022 Loan Agreement”) with Oxford. Pursuant to the terms of the 2022 Loan Agreement, the Company borrowed $60.0 million in term loans (the “Term Loans”), of which $31.6 million was used to repay the balance outstanding under the Amended Loan Agreement, including $0.2 million of accrued interest. Under the 2022 Loan Agreement the initial interest-only period was through April 1, 2025, followed by 23 equal monthly payments of principal and applicable interest. In September 2022, a qualifying equity event, as defined in the 2022 Loan Agreement, was achieved which extended the interest-only period through April 1, 2026, followed by 11 equal monthly payments of principal and applicable interest. As a result, all amounts outstanding under the 2022 Loan Agreement will mature on February 1, 2027 (the “Maturity Date”).
Debt instrument repayment number of month \| Months		23
Debt instrument repayment additional number of monthly payments due period extension \| Months		11
Amended Loan Agreement
Debt Instrument [Line Items]
Long-term debt				$ 30.0
Amount used to repay outstanding debt		$ 31.6
Payment of accrued interest		0.2
Debt instrument, fee amount		$ 1.5
Debt issuance costs			1.5
Term Loans
Debt Instrument [Line Items]
Long-term debt			$ 60.0
Debt instrument basis spread on variable rate			13.26%
Interest rate recognized under effective interest method			14.75%
Term Loans \| 2022 Loan Agreement
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate	7.94%	7.83%
Debt instrument floating per annum rate	1-Month CME Term Secured Overnight Financing Rate (“SOFR”)	30-day U.S. Dollar (USD) LIBOR
Debt instrument interest rate during period		0.11%
Debt instrument, final payment fee percentage		7.50%
Repayment of outstanding debt		$ 5.0

Poseida Therapeutics, Inc. 10-Q