Net Income (Loss) Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Numerator: [Abstract]
Net income (loss) attributable to AXT, Inc.	$ 2,229,000	$ 42,000	$ 3,422,000	$ (985,000)
Less: Preferred stock dividends	(44,000)	(44,000)	(132,000)	(132,000)
Net loss available to common stockholders	$ 2,185,000	$ (2,000)	$ 3,290,000	$ (1,117,000)
Basic net income (loss) per share [Abstract]
Basic (in dollars per share)	$ 0.07	$ 0.00	$ 0.10	$ (0.03)
Diluted net income (loss) per share [Abstract]
Diluted (in dollars per share)	$ 0.07	$ 0.00	$ 0.10	$ (0.03)
Denominator: [Abstract]
Denominator for basic net income (loss) per share - weighted average common shares (in shares)	32,110,000	31,988,000	32,043,000	32,262,000
Denominator for dilutive net income (loss) per common share (in shares)	33,138,000	31,988,000	32,615,000	32,262,000
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 (as a percent)			5.00%		5.00%
Liquidation preference over common stock (in dollars per share)	$ 4		$ 4		$ 4
Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)	652,000	3,037,000	910,000	3,037,000
Restricted Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)		466,000		466,000
Options [Member]
Denominator: [Abstract]
Effect of dilutive securities (in shares)	827,000		425,000
Restricted Stock Awards [Member]
Denominator: [Abstract]
Effect of dilutive securities (in shares)	201,000		147,000