Net Loss per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Numerator:
Net loss attributable to Forge Global Holdings, Inc., basic	$ (13,724)	$ (24,889)	$ (32,348)	$ (46,077)
Net loss attributable to common stockholders, diluted	$ (13,724)	$ (24,889)	$ (32,348)	$ (46,077)
Denominator:
Weighted-average number of shares used to compute net loss per share attributable to common stockholders, basic (in shares)	182,681,065	173,289,549	181,680,268	172,565,508
Weighted-average number of shares used to compute net loss per share attributable to common stockholders, diluted (in shares)	182,681,065	173,289,549	181,680,268	172,565,508
Net loss per share attributable to Forge Global Holdings, Inc. common stockholders:
Basic (in dollars per share)	$ (0.08)	$ (0.14)	$ (0.18)	$ (0.27)
Diluted (in dollars per share)	$ (0.08)	$ (0.14)	$ (0.18)	$ (0.27)