Net Loss Per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Numerator:
Net loss attributable to Forge Global Holdings, Inc., basic	$ (24,889)	$ (5,119)	$ (46,077)	$ (69,543)
Less: Decrease in fair value of public warrants	0	(28,757)	0	(10,291)
Net loss attributable to common stockholders, diluted	$ (24,889)	$ (33,876)	$ (46,077)	$ (79,834)
Denominator:
Weighted-average number of shares used to compute net loss per share attributable to common stockholders, basic (in shares)	173,289,549	167,052,900	172,565,508	116,815,363
Weighted-average number of shares used to compute net loss per share attributable to common stockholders, diluted (in shares)	173,289,549	173,578,093	172,565,508	120,584,585
Net loss per share attributable to Forge Global Holdings, Inc. common stockholders:
Basic (in dollars per share)	$ (0.14)	$ (0.03)	$ (0.27)	$ (0.60)
Diluted (in dollars per share)	$ (0.14)	$ (0.20)	$ (0.27)	$ (0.66)