The Company and Summary of Significant Accounting Policies- Principles of Consolidation (Details)			1 Months Ended													12 Months Ended
	May 31, 2023 USD ($)	Jan. 25, 2021 USD ($)	Dec. 31, 2023 USD ($)	Aug. 31, 2023 USD ($)	May 31, 2023 USD ($)	Jan. 31, 2023 USD ($)	Aug. 31, 2022 USD ($)	Jul. 31, 2022 USD ($)	May 31, 2022 USD ($)	Apr. 30, 2022 USD ($)	Jan. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	May 31, 2021 USD ($)	Feb. 28, 2021 USD ($)	Jan. 31, 2021 USD ($)	Dec. 31, 2023 USD ($) company	Dec. 31, 2022 USD ($) company	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2023 USD ($)	Jul. 31, 2023 USD ($)	Sep. 30, 2022	Oct. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of equity method investments | company																3	6
Investments, equity method			$ 12,476,000													$ 12,476,000	$ 12,720,000
Proceeds from sale of equity method investments																827,000
Payment for investment																$ 2,538,000
Sale of subsidiary shares to noncontrolling interests																		$ 1,151,000
Percentage of equity interest sold																15.00%
AXT-Tongmei, Inc | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Cash consideration												$ 1,000,000
Minority investors
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Loan amount	$ 300,000				$ 300,000	$ 200,000
Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd. | Loan from related party
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Increase in redeemable noncontrolling interests									$ 100,000
Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd. | Loan from related party | ChaoYang Xinshuo
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Loan amount																							$ 1,000,000.0	$ 900,000
Sale of subsidiary shares to noncontrolling interests										$ 1,900,000
Amount paid to subsidiary									600,000	700,000
Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd. | Loan from related party | Beijing Tongmei Xtal Technology
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Sale of subsidiary shares to noncontrolling interests										2,600,000
Amount paid to subsidiary									800,000	1,100,000
Increase in noncontrolling interest									$ 1,400,000		$ 2,200,000
Increase in redeemable noncontrolling interests											$ 200,000
Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Investment value, agreement amount													$ 1,800,000	$ 3,000,000.0
Investments, equity method														$ 1,800,000
Ownership (as a percent)								58.50%	58.50%		58.50%		58.50%	58.50%
Initial funding													$ 1,500,000	$ 1,500,000
Increase in noncontrolling interest								$ 610,000
Further investment								600,000
Redeemable noncontrolling interest increased								57,000
Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd. | Loan from related party
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Sale of subsidiary shares to noncontrolling interests										4,500,000
ChaoYang ShuoMei High Purity Semiconductor Materials Co., Ltd.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Investment value, agreement amount										4,400,000
Investments, equity method										$ 3,300,000
Ownership (as a percent)				75.00%						75.00%
Initial funding							$ 334,000
Increase in noncontrolling interest				$ 200,000			406,000
Increase in redeemable noncontrolling interests				44,000
Redeemable noncontrolling interest increased							73,000
ChaoYang KaiMei Quartz Co., Ltd
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Investment value, agreement amount										$ 7,600,000
Investments, equity method			$ 3,154,000	600,000		900,000				$ 3,000,000.0						$ 3,154,000	827,000			$ 2,300,000	$ 600,000
Ownership (as a percent)			40.00%							40.00%						40.00%
Initial funding								2,200,000
Investment amount								900,000
Additional investment																				$ 5,600,000
Payment for investment			$ 600,000
Emeishan Jia Mei High Purity Metals Co., Ltd Investment
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Investments, equity method																	$ 418,000
Ownership (as a percent)	25.00%		10.00%		25.00%											10.00%
Proceeds from sale of equity method investments	$ 10				$ 827,000
Percentage of equity interest sold	15.00%															15.00%
Percentage of ownership, cost method	10.00%		10.00%		10.00%											10.00%
ChaoYang ShuoMei High Purity Semiconductor Materials Co., Ltd.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Increase in noncontrolling interest					$ 400,000	200,000
Increase in redeemable noncontrolling interests					75,000	36,000
Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of outstanding shares																			33.00%
Beijing BoYu Semiconductor Vessel Craftwork Technology Co., Ltd Investment | Beijing Boyu Semiconductor Vessel Craftwork Technology Co Ltd
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Private equity ownership percentage																			7.59%
Beijing Tongmei Xtal Technology
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of ownership												85.50%
Percentage of outstanding shares		7.28%																				14.50%
Private equity ownership percentage		7.28%															14.50%
Percentage of key managers and contributors purchased																			0.40%
Investment in new facility		$ 49,000,000																	$ 48,100,000
Raised additional capital															$ 1,500,000
Transaction results in increase to noncontrolling interests												$ 1,200,000
Transaction results in increase to redeemable noncontrolling interests												$ 1,200,000
Increase in redeemable noncontrolling interests															$ 1,500,000				$ 48,100,000
Beijing Tongmei Xtal Technology | Beijing Boyu Semiconductor Vessel Craftwork Technology Co Ltd
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Investment amount														$ 900,000
Private equity ownership percentage																			7.59%
Beijing Tongmei Xtal Technology | Nanjing JinMei Gallium Co., Ltd
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Private equity ownership percentage																			0.0038%
Beijing Tongmei Xtal Technology | Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Loan amount											$ 1,400,000							$ 1,400,000
Beijing Tongmei Xtal Technology | Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd. | Loan from related party
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Increase in noncontrolling interest									$ 1,400,000
Beijing Tongmei Xtal Technology | Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Initial funding								800,000
Investment amount													$ 900,000
Further investment								$ 800,000
Nanjing JinMei Gallium Co., Ltd Investment
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of outstanding shares																			8.50%
Nanjing JinMei Gallium Co., Ltd Investment | Nanjing JinMei Gallium Co., Ltd
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Private equity ownership percentage																			0.38%
Nanjing JinMei Gallium Co., Ltd Investment | Emeishan Jia Mei High Purity Metals Co., Ltd Investment
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Ownership (as a percent)			25.00%													25.00%
Chao Yang XinMei High Purity Semiconductor Materials Co. Ltd. | ChaoYang ShuoMei High Purity Semiconductor Materials Co., Ltd.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Initial funding							$ 1,000,000.0
ChaoYang JinMei Gallium Ltd. | ChaoYang ShuoMei High Purity Semiconductor Materials Co., Ltd.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Loan amount						$ 500,000
ChaoYang JinMei Gallium Ltd. | ChaoYang ShuoMei High Purity Semiconductor Materials Co., Ltd. | ChaoYang ShuoMei High Purity Semiconductor Materials Co., Ltd.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Loan amount	$ 1,000,000.0			$ 600,000	$ 1,000,000.0