Net Loss Per Share - Reconciliation of Basic and Diluted Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Numerator:
Net loss attributable to AXT, Inc.	$ (2,937)	$ (5,823)	$ (6,536)	$ (14,260)
Less: Preferred stock dividends	(44)	(44)	(132)	(132)
Net loss available to common stockholders	$ (2,981)	$ (5,867)	$ (6,668)	$ (14,392)
Denominator:
Denominator for basic net income (loss) per share - weighted-average common shares	43,157	42,638	43,079	42,574
Effect of dilutive securities:
Denominator for dilutive net income (loss) per common shares	43,157	42,638	43,079	42,574
Net loss attributable to AXT, Inc. per common share:
Basic	$ (0.07)	$ (0.14)	$ (0.15)	$ (0.34)
Diluted	$ (0.07)	$ (0.14)	$ (0.15)	$ (0.34)
Common stock options
Net loss attributable to AXT, Inc. per common share:
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	1,186	1,200	1,186	1,200
Restricted Stock Awards
Net loss attributable to AXT, Inc. per common share:
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	1,518	1,006	1,518	1,006