Income Taxes - Composition of income tax (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Composition of income tax
Current income tax expense	¥ (42)	¥ 361	¥ 155
Deferred taxation			(53)
Total	¥ (42)	¥ 361	¥ 102

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration