Organization and business - Additional Information (Details) $ in Thousands, ¥ in Millions	1 Months Ended					6 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2024 CNY (¥)	Apr. 30, 2020 USD ($)	Apr. 30, 2020 CNY (¥)	May 31, 2017 USD ($)	Jun. 30, 2025 item	Dec. 31, 2024	Oct. 31, 2024	Sep. 30, 2024	Jun. 30, 2023	Dec. 31, 2019	Mar. 31, 2019	Aug. 31, 2018
Organization and business
Number of vehicles manufactured						60
Number of largest privately owned car manufacturers						3
Changchun Hualong Automotive Technology Co., Ltd., "Changchun Hualong"
Organization and business
Equity interests acquired (as a percent)			100.00%	100.00%
Wuhu Henglong Automotive Steering System Co., Ltd., "Wuhu"
Organization and business
Equity interest (as a percent)						100.00%	100.00%
Brazil Henglong
Organization and business
Equity interest (as a percent)					15.84%			94.19%	95.84%
Hubei Henglong & KYB Automobile Electric Steering System Co., Ltd., "Henglong KYB"
Organization and business
Equity interest (as a percent)	6.60%	6.60%				60.00%	66.60%						66.60%
Consideration for additional equity interest acquired	$ 15,500	¥ 110.0
Hyoseong (Wuhan) Motion Mechatronics System Co., Ltd., "Wuhan Hyoseong"
Organization and business
Equity interest (as a percent)						51.00%	51.00%					51.00%
Hubei Henglong formed Wuhu Hongrun New Material Co., Ltd "Wuhu Hongrun"
Organization and business
Equity interest (as a percent)											62.00%
Hanlin Chen
Organization and business
Equity interest (as a percent)			52.10%	52.10%
Third Party
Organization and business
Equity interest (as a percent)			47.90%	47.90%
CAAS Brazil's Imports and Trade In Automotive Parts Ltd., "Brazil Henglong"
Organization and business
Equity interest (as a percent)						94.19%	95.84%
Hubei Zhirong Automobile Technology Co., Ltd., "Zhirong"
Organization and business
Equity interest (as a percent)						100.00%	100.00%			100.00%
Changchun Hualong Automotive Technology Co., Ltd., "Changchun Hualong"
Organization and business
Consideration for additional equity interest acquired			$ 200	¥ 1.2
Brazil Henglong
Organization and business
Consideration for additional equity interest acquired \| $					$ 0