CONSOLIDATED STATEMENTS OF STOCKHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Series A-1 Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Common Stock Series A-1 Convertible Preferred Stock	Common Stock Series B Convertible Preferred Stock	Additional Paid-in Capital	Additional Paid-in Capital Series A-1 Convertible Preferred Stock	Additional Paid-in Capital Series B Convertible Preferred Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance at Dec. 31, 2021	$ 4,837			$ 3			$ 99,282				$ (94,448)
Beginning Balance (in shares) at Dec. 31, 2021				26,807,365
Exercise of stock options	128						128
Exercise of stock options, (in shares)				128,567
Stock-based compensation expense	437						437
Issuance of convertible preferred stock for the exercise of warrant		$ 24	$ 4					$ 24	$ 4
Issuance of convertible preferred stock for the exercise of warrant (in shares)					5,611	1,028
Issuance of common stock for the exercise of warrants (in shares)				137,285
Net Income (Loss)	(37,744)										(37,744)
Ending Balance at Dec. 31, 2022	(32,314)			$ 3			99,875				(132,192)
Ending Balance (in shares) at Dec. 31, 2022				27,079,856
Exercise of stock options	145						145
Exercise of stock options, (in shares)				298,562
Stock-based compensation expense	8,357						8,357
Issuance of convertible preferred stock for the exercise of warrant		$ 6	$ 89					$ 6	$ 89
Issuance of convertible preferred stock for the exercise of warrant (in shares)					492	8,530
Reverse recapitalization, net of transaction costs	58,573			$ 1			58,572
Reverse recapitalization, net of transaction costs (in shares)				13,735,872
Recognition of warrant liabilities in connection with the Merger	(13,762)						(13,762)
Issuance of common stock in connection with vesting of RSU awards				918,412
Issuance of common stock for the conversion of convertible notes	25,570			$ 1			25,569
Issuance of common stock for the conversion of convertible notes (in shares)				3,301,222
Recognition of earn-out liabilities (Note 3)	(53,040)						(53,040)
Reclassification of Legacy Allurion liabilitiy classified warrants to equity classification	929						929
Derecognition of liabilities associated with the Backstop Shares, Hunter shares, and the additional RTW and Fortress shares and issuance of related shares	16,098						16,098
Derecognition of liabilities associated with the Backstop Shares, Hunter shares, and the additional RTW and Fortress shares and issuance of related shares (in shares)				2,287,696
Issuance of common stock for the exercise of warrants	46						46
Issuance of common stock for the exercise of warrants (in shares)				21,943
Issuance of common stock for commitment shares for equity line financing	123						123
Issuance of common stock for commitment shares for equity line financing (in shares)				35,511
Other comprehensive loss	(700)									$ (700)
Net Income (Loss)	(80,607)										(80,607)
Ending Balance at Dec. 31, 2023	$ (70,487)			$ 5			$ 143,007			$ (700)	$ (212,799)
Ending Balance (in shares) at Dec. 31, 2023				47,688,096