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
Dec. 31, 2025
Dec. 31, 2024
Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Assets $ 3,618 $ 11,992
Total Liabilities 202 396
Level 1 | Public Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 202 396
Level 1 | Money Market Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Assets 3,618 11,992
Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 81,812 90,185
Level 3 | Legacy Allurion Common Stock Warrant Liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 2 41
Level 3 | Public Offering Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 397 3,630
Level 3 | July 2024 Private Placement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 30  
Level 3 | January 2025 Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 814  
Level 3 | February 2025 Offering Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 1,596  
Level 3 | November 2025 Private Placement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 2,788  
Level 3 | Revenue Interest Financing    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 47,700 49,200
Level 3 | Earn-out Liability    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 31 1,090
Level 3 | RTW Convertible Notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 28,070 35,710
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 370  
Level 3 | Private Placement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities   500
Total Carrying Value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Assets 3,618 11,992
Total Liabilities 82,014 90,581
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 41
Total Carrying Value | Public Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 202 396
Total Carrying Value | Public Offering Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 397 3,630
Total Carrying Value | July 2024 Private Placement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 30  
Total Carrying Value | January 2025 Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 814  
Total Carrying Value | February 2025 Offering Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 1,596  
Total Carrying Value | November 2025 Private Placement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 2,788  
Total Carrying Value | Revenue Interest Financing    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 47,700 49,200
Total Carrying Value | Earn-out Liability    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 31 1,090
Total Carrying Value | RTW Convertible Notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities 28,070 35,710
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 370  
Total Carrying Value | Money Market Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Assets $ 3,618 11,992
Total Carrying Value | Private Placement Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Liabilities   $ 500