Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands		Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock Common Stock Class A	Common Stock Common Stock Class B	Additional Paid- in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Statutory Surplus Reserve	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interests
Beginning balance (in shares) at Dec. 31, 2021	[1]			53,608,929	5,087,814
Beginning balance at Dec. 31, 2021		$ 811,665		$ 5	$ 1	$ 595,045	$ 63,732		$ 8,312	$ 9,109	$ 135,461
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		36,381					27,454				8,927
Foreign currency translation adjustment		(80,334)								(67,029)	(13,305)
Exercise of stock options (in shares)	[1]			763,584
Exercise of stock options		1,150				1,150
Stock-based compensation		5,236				5,236
Conversion of class B common stock to Class A common stock (in shares)	[1]			1,002	(1,002)
Conversion of Class B common stock to Class A common stock		1,002
Ending balance (in shares) at Sep. 30, 2022	[1]			54,373,515	5,086,812
Ending balance at Sep. 30, 2022		774,098		$ 5	$ 1	601,431	91,186		8,312	(57,920)	131,083
Beginning balance (in shares) at Jun. 30, 2022				54,141,805	5,086,812
Beginning balance at Jun. 30, 2022		787,145		$ 5	$ 1	599,138	70,182		8,312	(22,633)	132,140
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		27,076					21,004				6,072
Foreign currency translation adjustment		(42,416)								(35,287)	(7,129)
Exercise of stock options (in shares)				231,710
Exercise of stock options		400				400
Stock-based compensation		1,893				1,893
Ending balance (in shares) at Sep. 30, 2022	[1]			54,373,515	5,086,812
Ending balance at Sep. 30, 2022		774,098		$ 5	$ 1	601,431	91,186		8,312	(57,920)	131,083
Beginning balance (in shares) at Dec. 31, 2022				54,655,286	5,021,811
Beginning balance at Dec. 31, 2022		812,171
Beginning balance at Dec. 31, 2022		812,171	$ (1,769)	$ 5	$ 1	604,089	94,426	$ (1,769)	16,881	(40,546)	137,315
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		73,554					59,649				13,905
Foreign currency translation adjustment		(21,831)								(19,808)	(2,023)
Exercise of stock options (in shares)				919,448
Exercise of stock options		5,290		$ 1		1,455					3,834
ACM Shanghai dividend		(3,951)					0				(3,951)
Stock-based compensation		14,666				14,666
Conversion of Class B common stock to Class A common stock		0
Ending balance (in shares) at Sep. 30, 2023				55,574,734	5,021,811
Ending balance at Sep. 30, 2023		878,130
Ending balance at Sep. 30, 2023		878,130		$ 6	$ 1	620,210	152,306		16,881	(60,354)	149,080
Beginning balance (in shares) at Jun. 30, 2023				54,951,490	5,021,811
Beginning balance at Jun. 30, 2023		831,775		$ 5	$ 1	608,865	126,627		16,881	(61,916)	141,312
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		30,994					25,679				5,315
Foreign currency translation adjustment		4,015								1,562	2,453
Exercise of stock options (in shares)				623,244
Exercise of stock options		765		$ 1		764
Stock-based compensation		10,581				10,581
Ending balance (in shares) at Sep. 30, 2023				55,574,734	5,021,811
Ending balance at Sep. 30, 2023		878,130
Ending balance at Sep. 30, 2023		$ 878,130		$ 6	$ 1	$ 620,210	$ 152,306		$ 16,881	$ (60,354)	$ 149,080

[1] (1) Share numbers as of December 31, 2021 have been adjusted to reflect the three-for-one stock split effected in the form of a stock dividend in March 2022. See Note 2 for details.