Unaudited Quarterly Consolidated Financial Data (Details) - USD ($) $ / shares in Units, $ 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
Unaudited Quarterly Consolidated Financial Data
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 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
Net income (loss) attributable to AXT, Inc. per share, basic (in dollar per share)	$ 0.03	$ 0.14	$ 0.13	$ 0.07	$ 0.07	$ 0.09	$ 0.11	$ 0.08	$ 0.37	$ 0.35	$ 0.08
Net income (loss) attributable to AXT, Inc. per share, diluted (in dollar per share)	$ 0.03	$ 0.13	$ 0.13	$ 0.07	$ 0.07	$ 0.09	$ 0.10	$ 0.08	$ 0.37	$ 0.34	$ 0.07