Stockholders' Equity (Details) (USD $)	0 Months Ended	3 Months Ended		9 Months Ended			12 Months Ended
	Oct. 27, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period				$ 145,546,000	[1]
Common stock options exercised				134,000
Stock-based compensation				861,000
Net (loss) income		870,000	(2,065,000)	(404,000)		(5,625,000)
Dividends declared by joint ventures				(83,000)
Change in unrealized (loss) gain on marketable securities		(418,000)	73,000	(279,000)		26,000
Currency translation adjustment				(408,000)
Balance, end of period		145,367,000		145,367,000			145,546,000	[1]
Stock Repurchase Program [Abstract]
Stock repurchase program, authorized amount	5,000,000			6,000,000
Shares repurchased (in shares)				0			285,000
Average price of shares repurchased (in dollars per share)							$ 2.51
Total purchase price							716,000
Stock repurchase program remaining authorized repurchase amount							5,300,000
Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, end of period		3,532,000		3,532,000			3,532,000
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, end of period		32,000		32,000			32,000
Additional Paid In Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period				194,156,000
Common stock options exercised				134,000
Stock-based compensation				861,000
Balance, end of period		195,151,000		195,151,000
Accumulated Deficit [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period				(67,005,000)
Net (loss) income				(1,077,000)
Balance, end of period		(68,082,000)		(68,082,000)
Other Comprehensive Income/(Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period				8,953,000
Change in unrealized (loss) gain on marketable securities				(279,000)
Currency translation adjustment				(341,000)
Balance, end of period		8,333,000		8,333,000
AXT, Inc. Stockholders' Equity [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period				139,668,000
Common stock options exercised				134,000
Stock-based compensation				861,000
Net (loss) income				(1,077,000)
Change in unrealized (loss) gain on marketable securities				(279,000)
Currency translation adjustment				(341,000)
Balance, end of period		138,966,000		138,966,000
Noncontrolling Interests [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period				5,878,000
Net (loss) income				673,000
Dividends declared by joint ventures				(83,000)
Currency translation adjustment				(67,000)
Balance, end of period		$ 6,401,000		$ 6,401,000

[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.