Investments in Privately-Held Raw Material Companies - Minority Investment Entities (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2022 USD ($) entity	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Summarized income information of all the minority investment entities that are not consolidated and accounted for under the equity method [Abstract]
Revenue	$ 26,795	$ 35,183	$ 39,487	$ 39,653	$ 37,732	$ 34,576	$ 33,735	$ 31,350	$ 141,118	$ 137,393	$ 95,361
Gross profit	8,596	$ 14,782	$ 15,435	$ 13,308	12,139	$ 11,501	$ 12,238	$ 11,536	52,121	47,414	30,275
Net income									18,742	16,509	5,041
Minority investment entities
Assets, Current	183,545				160,185				183,545	160,185
Liabilities, Current	75,326				47,822				$ 75,326	47,822
Impaired entities | entity									1
Five Minority Investments
Summarized income information of all the minority investment entities that are not consolidated and accounted for under the equity method [Abstract]
Revenue									$ 48,139	35,939	20,049
Gross profit									27,000	17,465	4,907
Operating income									24,987	14,293	1,957
Net income									19,104	12,560	1,014
Minority investment entities
Assets, Current	43,091				27,503				43,091	27,503
Assets, Noncurrent	12,520				11,707				12,520	11,707
Liabilities, Current	$ 10,552				$ 5,799				10,552	5,799
Five Minority Investments
Minority investment entities
Entity income (loss) excluding impairment									6,000	4,400	100
Minority Investment Entities [Member]
Minority investment entities
Undistributed retained earnings									9,200	5,000
AXT, Inc. Stockholders' Equity
Summarized income information of all the minority investment entities that are not consolidated and accounted for under the equity method [Abstract]
Revenue									15,031	11,424	6,252
Gross profit									8,229	5,482	1,504
Operating income									7,532	4,495	504
Net income									$ 5,957	$ 4,409	$ 111