Stockholders' Equity and Stock Repurchase Program - Ownership Interest in Consolidated Subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stockholders' Equity and Stock Repurchase Program
Net income attributable to AXT, Inc.	$ 1,341	$ 5,759	$ 5,546	$ 3,165	$ 2,965	$ 3,800	$ 4,385	$ 3,425	$ 15,811	$ 14,575	$ 3,238
Decrease in additional paid-in capital for:
Investment in subsidiary with noncontrolling interest									(937)
Purchase of subsidiary shares from noncontrolling interests										(2,691)
Formation of new subsidiary with noncontrolling interests										(262)
Adjustment to noncontrolling interests in connection with the reorganization and alignment of assets under Tongmei										(1,229)
Changes in AXT, Inc.'s ownership interests in consolidated subsidiaries										(1,241)
Net transfers to noncontrolling interests									(937)	(5,423)
Change from net income attributable to AXT, Inc., net of transfers to noncontrolling interests									$ 14,874	$ 9,152