Net Income (loss) Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Numerator [Abstract]
Net income (loss) attributable to AXT, Inc.	$ 644	$ (2,295)	$ (1,077)	$ (6,730)
Less: Preferred stock dividends	(44)	(44)	(132)	(132)
Net income (loss) available to common stockholders	600	(2,339)	(1,209)	(6,862)
Denominator [Abstract]
Denominator for basic net income (loss) per share - weighted average common shares (in shares)	32,504	32,366	32,416	32,407
Effect Of Dilutive Securities On Earnings Per Share [Line Items]
Denominator for dilutive net income (loss) per common share (in shares)	32,738	32,366	32,416	32,407
Net loss attributable to AXT, Inc. per common share [Abstract]
Basic (in dollars per share)	$ 0.02	$ (0.07)	$ (0.04)	$ (0.21)
Diluted (in dollars per share)	$ 0.02	$ (0.07)	$ (0.04)	$ (0.21)
Weighted-average shares [Abstract]
Preferred stock, shares issued (in shares)	883		883		883
Preferred stock, shares outstanding (in shares)	883		883		883
Preferred stock, par value (in dollars per share)	$ 0.001		$ 0.001		$ 0.001
Preferred stock, value	$ 3,532		$ 3,532		$ 3,532	[1]
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 loss per share as the impact is anti-dilutive (in shares)	2,000	2,524	26,884	2,563
Restricted stock awards [Member]
Weighted-average shares [Abstract]
Securities excluded from diluted net loss per share as the impact is anti-dilutive (in shares)	77	243	250	242
Common stock options [Member]
Effect Of Dilutive Securities On Earnings Per Share [Line Items]
Effect of dilutive securities (in shares)	201	0	0	0
Restricted stock awards [Member]
Effect Of Dilutive Securities On Earnings Per Share [Line Items]
Effect of dilutive securities (in shares)	33	0	0	0

[1] Derived from the audited consolidated financial statements included in the Annual Report on Form 10-K filed with the SEC for the year ended December 31, 2013.