v3.26.1
Fair Value Measurements - Schedule of Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value at Issuance Date and on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Assets $ 3,707 $ 3,618
Total Liabilities 265 202
Level 1 | Public Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 265 202
Level 1 | Money Market Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Assets 3,707 3,618
Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 82,476 81,812
Level 3 | Legacy Allurion Common Stock Warrant Liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 2 2
Level 3 | Public Offering Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 239 397
Level 3 | January 2025 Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 140 814
Level 3 | February 2025 Offering Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 420 1,596
Level 3 | November 2025 Private Placement    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 1,209 2,788
Level 3 | Inducement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 2,800  
Level 3 | Revenue Interest Financing    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 48,800 47,700
Level 3 | Earn-out Liability    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 31 31
Level 3 | RTW Convertible Notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 28,550 28,070
Level 3 | Success Fee Derivative Liability    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 14 14
Level 3 | Share Obligation    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 250 370
Level 3 | July 2024 Private Placement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 21 30
Total Carrying Value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Assets 3,707 3,618
Total Liabilities 82,741 82,014
Total Carrying Value | Legacy Allurion Common Stock Warrant Liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 2 2
Total Carrying Value | Public Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 265 202
Total Carrying Value | Public Offering Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 239 397
Total Carrying Value | January 2025 Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 140 814
Total Carrying Value | February 2025 Offering Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 420 1,596
Total Carrying Value | November 2025 Private Placement    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 1,209 2,788
Total Carrying Value | Inducement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 2,800  
Total Carrying Value | Revenue Interest Financing    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 48,800 47,700
Total Carrying Value | Earn-out Liability    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 31 31
Total Carrying Value | RTW Convertible Notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 28,550 28,070
Total Carrying Value | Success Fee Derivative Liability    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 14 14
Total Carrying Value | Share Obligation    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 250 370
Total Carrying Value | Money Market Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Assets 3,707 3,618
Total Carrying Value | July 2024 Private Placement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities $ 21 $ 30