Net Loss Per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss attributable to Forge Global Holdings, Inc., basic	$ (111,859)	$ (18,499)	$ (9,712)
Less: Mark to market gain for Junior Preferred Stock warrants	(3,924)	0	0
Net loss attributable to common stockholders, diluted	$ (115,783)	$ (18,499)	$ (9,712)
Denominator:
Weighted-average number of shares used to compute net loss per share attributable to common stockholders, basic (in shares)	143,839,981	54,295,304	37,308,450
Dilutive effect of common share equivalents (in shares)	1,173,365	0	0
Dilutive effect of common share equivalents (in shares)	145,013,346	54,295,304	37,308,450
Net loss per share attributable to Forge Global Holdings, Inc. common stockholders:
Basic (in dollars per share)	$ (0.78)	$ (0.34)	$ (0.26)
Diluted (in dollars per share)	$ (0.80)	$ (0.34)	$ (0.26)