Stockholders' Equity and Stock Repurchase Program - Ownership Interest in Consolidated Subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stockholders' Equity and Stock Repurchase Program
Net income attributable to AXT, Inc.	$ (3,621)	$ (5,823)	$ (5,089)	$ (3,348)	$ 1,341	$ 5,759	$ 5,546	$ 3,165	$ (17,881)	$ 15,811	$ 14,575
Decrease in additional paid-in capital for:
Investment in subsidiary with noncontrolling interest									(308)	(937)
Change from net income (loss) attributable to AXT, Inc., net of transfers to noncontrolling interests									$ (18,189)	$ 14,874