Summary of Significant Accounting Policies - Selling, general and administrative expenses (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Summary of Significant Accounting Policies
Advertising costs	¥ 1,800,254	¥ 1,780,118	¥ 856,268

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 720
-SubTopic 35
-Name Accounting Standards Codification
-Section 55
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483385/720-35-55-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 720
-SubTopic 35
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483406/720-35-50-1

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration