Stockholders' Equity (Details) - USD ($)	3 Months Ended		12 Months Ended	108 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2015	Dec. 31, 2024	Oct. 27, 2014
Stockholders' Equity
Balance, beginning of period	$ 216,331,000	$ 227,483,000
Common stock options exercised		20,000
Noncontrolling interest portion of Tongmei stock-based compensation	(6,000)	(11,000)
Stock-based compensation	563,000	614,000
Tongmei stock-based compensation	83,000	195,000
Net loss	(9,408,000)	(1,977,000)
Other comprehensive income (loss)	484,000	(1,814,000)
Balance, end of period	208,047,000	224,510,000		$ 216,331,000
Net income (loss) attributable to redeemable noncontrolling interests	(608,000)	(71,000)
Other comprehensive income (loss) attributable to redeemable noncontrolling interests	53,000	189,000
Reclassification adjustment from AOCI	$ 0	$ 0
Stock repurchase program, authorized amount					$ 5,000,000
Shares repurchased (in shares)	0	0	908,000	0
Average price of shares repurchased (in dollars per share)			$ 2.52
Total purchase price			$ 2,300,000
Stock repurchase program remaining authorized repurchase amount	$ 2,700,000
Preferred Stock
Stockholders' Equity
Balance, beginning of period	3,532,000	$ 3,532,000
Balance, end of period	3,532,000	3,532,000		$ 3,532,000
Common Stock
Stockholders' Equity
Balance, beginning of period	45,000	44,000
Noncontrolling interest portion of Tongmei stock-based compensation	1,000
Balance, end of period	46,000	44,000		45,000
Additional Paid-In Capital
Stockholders' Equity
Balance, beginning of period	241,514,000	238,452,000
Common stock options exercised		20,000
Noncontrolling interest portion of Tongmei stock-based compensation	(13,000)	(24,000)
Stock-based compensation	563,000	614,000
Tongmei stock-based compensation	83,000	195,000
Balance, end of period	242,147,000	239,257,000		241,514,000
Accumulated Deficit
Stockholders' Equity
Balance, beginning of period	(43,664,000)	(32,040,000)
Net loss	(8,798,000)	(2,083,000)
Balance, end of period	(52,462,000)	(34,123,000)		(43,664,000)
Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity
Balance, beginning of period	(8,657,000)	(5,999,000)
Other comprehensive income (loss)	431,000	(1,627,000)
Balance, end of period	(8,226,000)	(7,626,000)		(8,657,000)
AXT, Inc. Stockholders' Equity
Stockholders' Equity
Balance, beginning of period	192,770,000	203,989,000
Common stock options exercised		20,000
Noncontrolling interest portion of Tongmei stock-based compensation	(12,000)	(24,000)
Stock-based compensation	563,000	614,000
Tongmei stock-based compensation	83,000	195,000
Net loss	(8,798,000)	(2,083,000)
Other comprehensive income (loss)	431,000	(1,627,000)
Balance, end of period	185,037,000	201,084,000		192,770,000
Noncontrolling Interests
Stockholders' Equity
Balance, beginning of period	23,561,000	23,494,000
Noncontrolling interest portion of Tongmei stock-based compensation	6,000	13,000
Net loss	(610,000)	106,000
Other comprehensive income (loss)	53,000	(187,000)
Balance, end of period	$ 23,010,000	$ 23,426,000		$ 23,561,000