Subsequent events (Details) - Subsequent Event - CNY (¥)	1 Months Ended
Apr. 30, 2023	Mar. 31, 2023	Feb. 28, 2023	Jan. 31, 2023
One-year loans
Subsequent events
Interest rate (in percent)	8.00%	4.25%	5.50%	4.00%
Capital contribution by owner	¥ 200,000,000	¥ 47,500,000	¥ 10,000,000	¥ 255,000,000
Nine-month loan
Subsequent events
Interest rate (in percent)		8.00%
Capital contribution by owner		¥ 100,000,000

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant