Net Income (loss) Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Numerator:
Net income attributable to AXT, Inc.	$ (2,400)	$ 1,635
Less: Preferred stock dividends	(44)	(44)
Net income (loss) available to common stockholders	(2,444)	1,591
Denominator:
Denominator for basic net income per share-weighted average common shares (in shares)	32,297	32,034
Effect of Dilutive Securities on Earnings Per Share [Line Items]
Denominator for dilutive net income (loss) per share (in shares)	32,297	33,018
Net income (loss) attributable to AXT, Inc. per common share:
Net income (loss) attributable to AXT, Inc. (in dollars per share)	$ (0.08)	$ 0.05
Net income (loss) to common stockholders (in dollars per share)	$ (0.08)	$ 0.05
Weighted-average shares: [Abstract]
Preferred stock, shares issued (in shares)	883		883
Preferred stock, shares outstanding (in shares)	883		883
Preferred stock, par value (in dollars per share)	$ 0.001		$ 0.001
Preferred stock, value	$ 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
Options [Member]
Weighted-average shares: [Abstract]
Securities excluded from diluted net income per share as the impact is anti-dilutive (in shares)	2,656	878
Restricted stock awards [Member]
Weighted-average shares: [Abstract]
Securities excluded from diluted net income per share as the impact is anti-dilutive (in shares)	239	74
Common stock options [Member]
Effect of Dilutive Securities on Earnings Per Share [Line Items]
Effect of dilutive securities (in shares)	0	903
Restricted stock awards [Member]
Effect of Dilutive Securities on Earnings Per Share [Line Items]
Effect of dilutive securities (in shares)	0	81

[1] The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited consolidated financial statements at that date.