Net Loss Per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss attributable to Forge Global Holdings, Inc., basic	$ (90,221)	$ (111,859)	$ (18,499)
Less: Change in fair value of Junior Preferred Stock warrant liability	0	(3,924)	0
Net loss attributable to common stockholders, diluted	$ (90,221)	$ (115,783)	$ (18,499)
Denominator:
Weighted-average number of shares used to compute net loss per share attributable to common stockholders, basic (in shares)	173,402,167	143,839,981	54,295,304
Dilutive effect of common share equivalents (in shares)	0	1,173,365	0
Dilutive effect of common share equivalents (in shares)	173,402,167	145,013,346	54,295,304
Net loss per share attributable to Forge Global Holdings, Inc. common stockholders:
Basic (in dollars per share)	$ (0.52)	$ (0.78)	$ (0.34)
Diluted (in dollars per share)	$ (0.52)	$ (0.80)	$ (0.34)