Land use right net (Details) - ZHEJIANG TIANLAN - CNY (¥) ¥ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Land use right, gross	¥ 7,361	¥ 7,361
Less: accumulated amortization	(2,364)	(2,214)
Land use right, net	¥ 4,997	¥ 5,147

Gross carrying amount before accumulated amortization as of the balance sheet date of an intangible asset that arises from a contractual arrangement with a third party (not including franchise rights and license agreements).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Name:	us-gaap_FiniteLivedContractualRightsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant