Commitments and Contingencies (Details) $ in Thousands			12 Months Ended
	Aug. 27, 2021 board_member officer	Apr. 09, 2021 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2024 USD ($)
Loss Contingencies [Line Items]
Termination fee		$ 100
Accrued litigation settlement (Note 13)			$ 12,000	$ 12,000
Litigation insurance reimbursement receivable (Note 13)			5,000	$ 5,000
McIntosh v. Katapult Holdings, Inc., et all | Settled Litigation
Loss Contingencies [Line Items]
Accrued litigation settlement (Note 13)			12
Litigation expense, net			7
Estimated insurance reimbursement			5
McIntosh v. Katapult Holdings, Inc., et all | Legacy Katapult | Officer | Settled Litigation
Loss Contingencies [Line Items]
Number of defendants | officer	3
Number of defendants dismissed | board_member	2
McIntosh v. Katapult Holdings, Inc., et all | FinServ | Officer | Settled Litigation
Loss Contingencies [Line Items]
Number of defendants | officer	2
Litigation insurance reimbursement receivable (Note 13)			$ 5