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
	Mar. 31, 2025	Mar. 31, 2024
Numerator:
Net income (loss) attributable to AXT, Inc.	$ (8,798)	$ (2,083)
Less: Preferred stock dividends	(44)	(44)
Net income (loss) available to common stockholders	$ (8,842)	$ (2,127)
Denominator:
Denominator for basic net income (loss) per share - weighted-average common shares	43,554	42,987
Effect of dilutive securities:
Denominator for dilutive net income (loss) per common shares	43,554	42,987
Net loss attributable to AXT, Inc. per common share:
Basic	$ (0.2)	$ (0.05)
Diluted	$ (0.2)	$ (0.05)
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)	1,175	1,189
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)	2,006	1,401