Other income and other losses (Details 1) - ZHEJIANG TIANLAN - CNY (¥) ¥ in Thousands	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Impairment loss on short term investments	¥ 0	¥ 0	¥ 195
Impairment loss on contract assets	0	0	3,560
Other losses	¥ 0	¥ 0	¥ 3,755

Amount of gain (loss) related to nonoperating activities, classified as other.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(7))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(9))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration