Net Loss Per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Numerator:
Net loss attributable to Forge Global Holdings, Inc., basic	$ (21,188)	$ (64,424)
Net loss attributable to common stockholders, diluted	$ (21,188)	$ (64,424)
Denominator:
Weighted-average number of shares used to compute net loss per share attributable to common stockholders, basic (in shares)	171,816,522	66,007,461
Weighted-average number of shares used to compute net loss per share attributable to common stockholders, diluted (in shares)	171,816,522	66,007,461
Net loss per share attributable to Forge Global Holdings, Inc. common stockholders:
Basic (in dollars per share)	$ (0.12)	$ (0.98)
Diluted (in dollars per share)	$ (0.12)	$ (0.98)