Investments in Privately Held Companies (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($) item	Jun. 30, 2016 USD ($) employee entity	Jun. 30, 2015 USD ($) item	Jun. 30, 2016 employee	Jun. 30, 2016 item	Jun. 30, 2016 entity	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2015 entity
Summary of investments [Abstract]
Income allocated to minority interests	$ (353,000)	$ 127,000	$ (462,000)	$ 252,000
Equity investments classified as other assets								$ 12,787,000	$ 14,114,000
Investments in unconsolidated privately-held entities, included in other assets								3
Joint Ventures [Member]
Summary of investments [Abstract]
Number of consolidated joint ventures		3		3		3	3			3
Income from three consolidated joint ventures	(306,000)	$ 647,000	(481,000)	$ 1,200,000
Income allocated to minority interests	(353,000)	127,000	(462,000)	252,000
Net income from joint ventures attributable to parent	47,000	520,000	$ (19,000)	947,000
Minority investments | entity			4
Other Assets [Member] | Joint Ventures [Member]
Summary of investments [Abstract]
Minority investment in consolidated joint venture, included in other assets								3,700,000	4,100,000
AXT, Inc. Stockholders' Equity
Summary of investments [Abstract]
Gross equity earnings from minority-owned joint ventures that are not consolidated, recorded as other income	(1,644,000)	1,784,000	$ (3,418,000)	2,741,000
Equity Method Investments [Member]
Summary of investments [Abstract]
Equity method investment by parent								7,459,000	7,948,000
Equity investments classified as other assets								7,400,000	7,900,000
Gross equity earnings from minority-owned joint ventures that are not consolidated, recorded as other income	$ (400,000)	$ 410,000	$ (856,000)	$ 610,000
Minority investments not consolidated accounted for under equity method | entity			7
Beijing JiYa Semiconductor Material Co., Ltd [Member]
Summary of investments [Abstract]
Investments, consolidated								3,331,000	3,331,000
Percentage of ownership, consolidated method (in hundredths)			46.00%
Employee duration			27 years
Number of persons on board | employee					1
Beijing JiYa Semiconductor Material Co., Ltd [Member] | Joint Ventures [Member]
Summary of investments [Abstract]
Minority investments | entity			3
Nanjing Jin Mei Gallium Co., Ltd [Member]
Summary of investments [Abstract]
Investments, consolidated								592,000	592,000
Percentage of ownership, consolidated method (in hundredths)			83.00%
Number of new board representatives | employee			2
Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd [Member]
Summary of investments [Abstract]
Investments, consolidated								1,346,000	1,346,000
Percentage of ownership, consolidated method (in hundredths)			70.00%
Number of new board representatives | employee			2
Donghai County Dongfang High Purity Electronic Materials Co., Ltd [Member] | Equity Method Investments [Member]
Summary of investments [Abstract]
Equity method investment by parent								1,489,000	1,524,000
Percentage of ownership, equity method (in hundredths)	46.00%		46.00%
Xilingol Tongli Germanium Co. Ltd [Member] | Equity Method Investments [Member]
Summary of investments [Abstract]
Equity method investment by parent								4,895,000	5,343,000
Percentage of ownership, equity method (in hundredths)	25.00%		25.00%
Emeishan Jia Mei High Purity Metals Co., Ltd [Member] | Equity Method Investments [Member]
Summary of investments [Abstract]
Equity method investment by parent								1,075,000	1,081,000
Percentage of ownership, equity method (in hundredths)	25.00%		25.00%
Jinmei [Member] | Joint Ventures [Member]
Summary of investments [Abstract]
Minority investments | entity			1
Majority-Owned Subsidiaries [Member]
Summary of investments [Abstract]
Investments, consolidated								$ 5,269,000	$ 5,269,000