UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Redeemable Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance at Dec. 31, 2022	$ (32,314)		$ 3	$ 99,875		$ (132,192)
Beginning Balance (in shares) at Dec. 31, 2022			27,079,856
Exercise of stock options	20			20
Exercise of stock options, (in shares)			15,376
Issuance of Legacy Allurion convertible preferred stock for the exercise of warrants	29			29
Issuance of Legacy Allurion convertible preferred stock for the exercise of warrants (in shares)			3,554
Stock-based compensation expense	409			409
Net Income (Loss)	(17,801)					(17,801)
Ending Balance at Mar. 31, 2023	(49,657)		$ 3	100,333		(149,993)
Ending Balance (in shares) at Mar. 31, 2023			27,098,786
Beginning Balance at Dec. 31, 2022	(32,314)		$ 3	99,875		(132,192)
Beginning Balance (in shares) at Dec. 31, 2022			27,079,856
Net Income (Loss)	(61,427)
Ending Balance at Sep. 30, 2023	(52,756)		$ 5	140,858	$ 0	(193,619)
Ending Balance (in shares) at Sep. 30, 2023			47,460,941
Beginning Balance at Mar. 31, 2023	(49,657)		$ 3	100,333		(149,993)
Beginning Balance (in shares) at Mar. 31, 2023			27,098,786
Exercise of stock options	28			28
Exercise of stock options, (in shares)			27,626
Issuance of Legacy Allurion convertible preferred stock for the exercise of warrants	6			6
Issuance of Legacy Allurion convertible preferred stock for the exercise of warrants (in shares)			492
Stock-based compensation expense	401			401
Net Income (Loss)	(21,996)					(21,996)
Ending Balance at Jun. 30, 2023	(71,218)		$ 3	100,768		(171,989)
Ending Balance (in shares) at Jun. 30, 2023			27,126,904
Exercise of stock options	83			83
Exercise of stock options, (in shares)			77,214
Issuance of Legacy Allurion convertible preferred stock for the exercise of warrants	60			60
Issuance of Legacy Allurion convertible preferred stock for the exercise of warrants (in shares)			4,976
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 for the exercise of Public Warrants	42			42
Issuance of common stock for the exercise of Public Warrants (in shares)			20,506
Issuance of common stock in connection with vesting of RSU awards (in shares)			906,551
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
Stock-based compensation expense	5,539			5,539
Net Income (Loss)	(21,630)				0	(21,630)
Ending Balance at Sep. 30, 2023	$ (52,756)		$ 5	140,858	0	(193,619)
Ending Balance (in shares) at Sep. 30, 2023			47,460,941
Issuance of preferred stock in connection with Private Placement, net of issuance costs (in shares)	0
Ending Balance, temporary stocks (in shares)	0
Beginning Balance at Dec. 31, 2023	$ (70,487)		$ 5	143,007	(700)	(212,799)
Beginning Balance (in shares) at Dec. 31, 2023			47,688,096
Exercise of stock options	9			9
Exercise of stock options, (in shares)			4,646
Issuance of common stock for the exercise of Public Warrants (in shares)			142
Stock issued during period value	378			378
Stock isssued during the period (in shares)			143,234
Issuance of common stock in connection with vesting of RSU awards (in shares)			62,619
Stock-based compensation expense	552			552
Other comprehensive income (loss)	(2,200)				(2,200)
Net Income (Loss)	5,586					5,586
Ending Balance at Mar. 31, 2024	(66,162)		$ 5	143,946	(2,900)	(207,213)
Ending Balance (in shares) at Mar. 31, 2024			47,898,737
Beginning Balance at Dec. 31, 2023	(70,487)		$ 5	143,007	(700)	(212,799)
Beginning Balance (in shares) at Dec. 31, 2023			47,688,096
Net Income (Loss)	(5,580)
Ending Balance at Sep. 30, 2024	(64,790)		$ 7	150,692	2,890	(218,379)
Ending Balance (in shares) at Sep. 30, 2024			64,369,381
Beginning Balance at Mar. 31, 2024	(66,162)		$ 5	143,946	(2,900)	(207,213)
Beginning Balance (in shares) at Mar. 31, 2024			47,898,737
Exercise of stock options	16			16
Exercise of stock options, (in shares)			11,491
Issuance of common stock for the exercise of Public Warrants	1			1
Issuance of common stock for the exercise of Public Warrants (in shares)			142
Issuance of common stock in connection with vesting of RSU awards (in shares)			62,619
Stock-based compensation expense	805			805
Other comprehensive income (loss)	(3,080)				(3,080)
Net Income (Loss)	(2,162)					(2,162)
Ending Balance at Jun. 30, 2024	(70,582)		$ 5	144,768	(5,980)	(209,375)
Ending Balance (in shares) at Jun. 30, 2024			47,972,989
Stock issued during period value	5,066		$ 2	5,064
Stock isssued during the period (in shares)			16,333,773
Issuance of common stock in connection with vesting of RSU awards (in shares)			62,619
Stock-based compensation expense	860			860
Issuance of preferred stock in connection with Private Placement, net of issuance costs (in shares)		2,260,159
Issuance of preferred stock in connection with Private Placement, net of issuance costs		$ 979
Other comprehensive income (loss)	8,870				8,870
Net Income (Loss)	(9,004)					(9,004)
Ending Balance at Sep. 30, 2024	$ (64,790)		$ 7	$ 150,692	$ 2,890	$ (218,379)
Ending Balance (in shares) at Sep. 30, 2024			64,369,381
Issuance of preferred stock in connection with Private Placement, net of issuance costs (in shares)	2,260,159
Ending Balance, temporary stocks (in shares)	2,260,159	2,260,159
Ending Balance, temporary stocks	$ 979	$ 979