Stockholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Mar. 31, 2013 Preferred Stock [Member]	Dec. 31, 2012 Preferred Stock [Member]	Mar. 31, 2013 Common Stock [Member]	Dec. 31, 2012 Common Stock [Member]	Mar. 31, 2013 Additional Paid In Capital [Member]	Mar. 31, 2013 Accumulated Deficit [Member]	Mar. 31, 2013 Other Comprehensive Income/(loss) [Member]	Mar. 31, 2013 AXT, Inc. stockholders equity [Member]	Mar. 31, 2013 Noncontrolling interests [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 150,914	[1]		$ 3,532	$ 3,532	$ 32	$ 32	$ 193,063	$ (59,047)	$ 6,033	$ 143,613	$ 7,301
Common stock options exercised	256							256			256
Stock-based compensation	332							332			332
Comprehensive income:
Net loss	(1,959)		2,952						(2,400)		(2,400)	441
Dividends declared by joint ventures	(2,897)											(2,897)
Change in unrealized (loss) gain on marketable securities	(17)		100							(17)	(17)
Currency translation adjustment	407									350	350	57
Balance, end of period	$ 147,036			$ 3,532	$ 3,532	$ 32	$ 32	$ 193,651	$ (61,447)	$ 6,366	$ 142,134	$ 4,902

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