Net Income (Loss) Per Share (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Numerator: [Abstract]
Net income (loss) attributable to AXT, Inc.	$ 42,000	$ (1,024,000)
Less: Preferred stock dividends	(44,000)	(44,000)
Net loss available to common stockholders	$ (2,000)	$ (1,068,000)
Basic net income (loss) per share [Abstract]
Basic (in dollars per share)	$ 0.00	$ (0.03)
Diluted net income (loss) per share [Abstract]
Diluted (in dollars per share)	$ 0.00	$ (0.03)
Denominator: [Abstract]
Denominator for basic net loss per share - weighted average common shares (in shares)	32,002,000	32,553,000
Denominator for dilutive net loss per common share (in shares)	32,002,000	32,553,000
Preferred stock, shares issued (in shares)	883,000		883,000
Preferred stock, shares outstanding (in shares)	883,000		883,000
Preferred stock, par value (in dollars per share)	$ 0.001		$ 0.001
Preferred stock, value	$ 3,532,000		$ 3,532,000
Cumulative annual dividend rate (as a percent)	5.00%		5.00%
Liquidation preference over common stock (in dollars per share)	$ 4		$ 4
Options [Member]
Weighted-average shares: [Abstract]
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	3,313,000	3,167,000
Restricted Stock Awards [Member]
Weighted-average shares: [Abstract]
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	339,000	261,000