Net Income (Loss) Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Numerator: [Abstract]
Net income (loss) attributable to AXT, Inc.	$ 42,000	$ 644,000	$ (985,000)	$ (1,077,000)
Less: Preferred stock dividends	(44,000)	(44,000)	(132,000)	(132,000)
Net income (loss) available to common stockholders	$ (2,000)	$ 600,000	$ (1,117,000)	$ (1,209,000)
Denominator: [Abstract]
Denominator for basic net income (loss) per share - weighted average common shares (in shares)	31,988,000	32,504,000	32,262,000	32,416,000
Effect of dilutive securities:
Denominator for dilutive net income (loss) per common share (in shares)	31,988,000	32,738,000	32,262,000	32,416,000
Basic net income (loss) per share [Abstract]
Basic (in dollars per share)	$ 0.00	$ 0.02	$ (0.03)	$ (0.04)
Diluted net income (loss) per share [Abstract]
Diluted (in dollars per share)	$ 0.00	$ 0.02	$ (0.03)	$ (0.04)
Weighted-average shares: [Abstract]
Preferred stock, shares issued (in shares)	883,000		883,000		883,000
Preferred stock, shares outstanding (in shares)	883,000		883,000		883,000
Preferred stock, par value (in dollars per share)	$ 0.001		$ 0.001		$ 0.001
Preferred stock, value	$ 3,532,000		$ 3,532,000		$ 3,532,000
Cumulative annual dividend rate (in hundredths)			5.00%		5.00%
Liquidation preference over common stock (in dollars per share)	$ 4		$ 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)	3,037,000	2,000,000	3,037,000	2,684,000
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)	466,000	77,000	466,000	250,000
Options [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)		201,000
Restricted Stock Awards [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)		33,000