Unaudited Condensed Consolidated Statements of Changes in Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Previously Reported	Revision of Prior Period, Adjustment	Common Stock	Common Stock Previously Reported	Common Stock Revision of Prior Period, Adjustment	Additional Paid-In Capital	Additional Paid-In Capital Previously Reported	Additional Paid-In Capital Revision of Prior Period, Adjustment	Accumulated Deficit	Accumulated Deficit Previously Reported	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Previously Reported	Noncontrolling Interest	Noncontrolling Interest Previously Reported
Beginning balance (in shares) at Dec. 31, 2021	73,914,149	23,668,198	50,245,951
Beginning balance at Dec. 31, 2021	$ 246,056	$ 246,056
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of preferred stock to common stock (in shares)	(73,914,149)
Conversion of preferred stock to common stock	$ (246,056)
Ending balance (in shares) at Mar. 31, 2022	0
Ending balance at Mar. 31, 2022	$ 0
Beginning balance (in shares) at Dec. 31, 2021				63,090,701	20,269,864	43,031,139
Beginning balance at Dec. 31, 2021	(52,640)	$ (52,640)		$ 5		$ 5	$ 25,914	$ 25,919	$ (5)	$ (78,559)	$ (78,559)	$ 0	$ 0	$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Pre-close issuance of common stock upon exercise of vested options (in shares)				190,505
Pre-close issuance of common stock upon exercise of vested options	102						102
Pre-close issuance of common stock upon exercise of unvested options (in shares)				4,472
Pre-close issuance of common stock for services (in shares)				62,952
Pre-close issuance of common stock for services	621						621
Conversion of preferred stock to common stock (in shares)				73,914,149
Conversion of preferred stock to common stock	246,056			$ 7			246,049
Conversion of May 2020 and October 2020 preferred stock warrants of Legacy Forge to common stock warrants	2,949						2,949
Settlement of promissory notes	4,207			$ 2			4,205
Issuance of common stock upon Merger (net of redemptions), including PIPE and A&R FPA investors, net of transaction costs (in shares)				31,961,047
Issuance of common stock upon Merger (net of redemptions), including PIPE and A&R FPA investors, net of transaction costs	140,811			$ 3			140,808
Vesting of early exercised stock options and restricted stock awards	409						409
Share-based compensation expense	7,948						7,948
Net loss	(64,424)									(64,424)
Ending balance (in shares) at Mar. 31, 2022				169,223,826
Ending balance at Mar. 31, 2022	$ 286,039			$ 17			429,005			(142,983)		0		0
Beginning balance (in shares) at Dec. 31, 2021	73,914,149	23,668,198	50,245,951
Beginning balance at Dec. 31, 2021	$ 246,056	$ 246,056
Ending balance (in shares) at Sep. 30, 2022	0
Ending balance at Sep. 30, 2022	$ 0
Beginning balance (in shares) at Dec. 31, 2021				63,090,701	20,269,864	43,031,139
Beginning balance at Dec. 31, 2021	(52,640)	$ (52,640)		$ 5		$ 5	25,914	$ 25,919	$ (5)	(78,559)	$ (78,559)	0	$ 0	0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Pre-close issuance of common stock for services							600
Net loss	(85,741)
Foreign currency translation adjustment	(159)
Ending balance (in shares) at Sep. 30, 2022				172,442,676
Ending balance at Sep. 30, 2022	$ 337,809			$ 18			496,592			(164,300)		(95)		5,594
Beginning balance (in shares) at Mar. 31, 2022	0
Beginning balance at Mar. 31, 2022	$ 0
Ending balance (in shares) at Jun. 30, 2022	0
Ending balance at Jun. 30, 2022	$ 0
Beginning balance (in shares) at Mar. 31, 2022				169,223,826
Beginning balance at Mar. 31, 2022	286,039			$ 17			429,005			(142,983)		0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of Public Warrants (in shares)				1,994,022
Issuance of common stock upon exercise of Public Warrants	23,629						23,629
Issuance of common stock upon exercise of vested options (in shares)				146,232
Issuance of common stock upon exercise of vested options	401						401
Vesting of early exercised stock options and restricted stock awards	638						638
Share-based compensation expense	10,903						10,903
Net loss	(5,119)									(5,119)
Ending balance (in shares) at Jun. 30, 2022				171,364,080
Ending balance at Jun. 30, 2022	$ 316,491			$ 17			464,576			(148,102)		0		0
Ending balance (in shares) at Sep. 30, 2022	0
Ending balance at Sep. 30, 2022	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon release of restricted stock units (in shares)				43,142
Issuance of common stock upon exercise of Public Warrants (in shares)				768
Issuance of common stock upon exercise of Public Warrants	9						9
Issuance of common stock upon exercise of vested options (in shares)				622,929
Issuance of common stock upon exercise of vested options	365						364
Pre-close issuance of common stock upon exercise of unvested options (in shares)				78,076
Issuance of common stock upon exercise of Junior Preferred Stock Warrants (in shares)				123,379
Issuance of common stock upon exercise of Junior Preferred Stock Warrants	653						653
Issuance of common stock upon Merger (in shares)				210,302
Formation of Forge Europe	9,488						3,830							5,658
Vesting of early exercised stock options and restricted stock awards	193						193
Share-based compensation expense	26,967						26,967
Net loss	(16,198)									(16,198)
Foreign currency translation adjustment	(159)											(95)		(64)
Ending balance (in shares) at Sep. 30, 2022				172,442,676
Ending balance at Sep. 30, 2022	337,809			$ 18			496,592			(164,300)		(95)		5,594
Beginning balance (in shares) at Dec. 31, 2022				172,560,916
Beginning balance at Dec. 31, 2022	325,461			$ 18			509,094			(190,418)		693		6,074
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon release of restricted stock units (in shares)				1,464,968
Tax withholding related to vesting of restricted stock units (in shares)				(326,812)
Tax withholding related to vesting of restricted stock units	(557)						(557)
Repurchase of early exercised stock options (in shares)				(8,132)
Issuance of common stock upon exercise of vested options (in shares)				117,215
Issuance of common stock upon exercise of vested options	61						61
Vesting of early exercised stock options and restricted stock awards	131						131
Share-based compensation expense	7,401						7,401
Net loss	(21,261)									(21,188)				(73)
Foreign currency translation adjustment	228											137		91
Ending balance (in shares) at Mar. 31, 2023				173,808,155
Ending balance at Mar. 31, 2023	311,464			$ 18			516,130			(211,606)		830		6,092
Beginning balance (in shares) at Dec. 31, 2022				172,560,916
Beginning balance at Dec. 31, 2022	325,461			$ 18			509,094			(190,418)		693		6,074
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(65,318)
Foreign currency translation adjustment	(158)
Ending balance (in shares) at Sep. 30, 2023				175,173,113
Ending balance at Sep. 30, 2023	285,550			$ 18			534,659			(254,843)		601		5,115
Beginning balance (in shares) at Mar. 31, 2023				173,808,155
Beginning balance at Mar. 31, 2023	311,464			$ 18			516,130			(211,606)		830		6,092
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon release of restricted stock units (in shares)				243,473
Issuance of common stock upon exercise of vested options (in shares)				335,085
Issuance of common stock upon exercise of vested options	269						269
Vesting of early exercised stock options and restricted stock awards	67						67
Share-based compensation expense	8,809						8,809
Net loss	(25,100)									(24,889)				(211)
Foreign currency translation adjustment	(53)											(32)		(21)
Ending balance (in shares) at Jun. 30, 2023				174,386,713
Ending balance at Jun. 30, 2023	295,456			$ 18			525,275			(236,495)		798		5,860
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon release of restricted stock units (in shares)				740,880
Repurchase of early exercised stock options (in shares)				(194,400)
Issuance of common stock upon exercise of vested options (in shares)				239,920
Issuance of common stock upon exercise of vested options	124						124
Vesting of early exercised stock options and restricted stock awards	27						27
Share-based compensation expense	9,233						9,233
Net loss	(18,957)									(18,348)				(609)
Foreign currency translation adjustment	(333)											(197)		(136)
Ending balance (in shares) at Sep. 30, 2023				175,173,113
Ending balance at Sep. 30, 2023	$ 285,550			$ 18			$ 534,659			$ (254,843)		$ 601		$ 5,115