Fair value measurement of financial instruments - Disclosure of Financial assets measured at fair value (Details) - CNY (¥) ¥ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Disclosure of Fair Value of Financial Instruments [Line Items]
Assets	¥ 7,145,853	¥ 7,693,770
Recurring fair value measurement [member] \| Financial assets at fair value through profit or loss, category [member]
Disclosure of Fair Value of Financial Instruments [Line Items]
Assets	1,793,484	1,742,065
Recurring fair value measurement [member] \| Financial assets at fair value through profit or loss, category [member] \| Level 1 of fair value hierarchy [member]
Disclosure of Fair Value of Financial Instruments [Line Items]
Assets	40,871	56,919
Recurring fair value measurement [member] \| Financial assets at fair value through profit or loss, category [member] \| Level 2 of fair value hierarchy [member]
Disclosure of Fair Value of Financial Instruments [Line Items]
Assets	1,735,333	1,685,146
Recurring fair value measurement [member] \| Financial assets at fair value through profit or loss, category [member] \| Level 3 of fair value hierarchy [member]
Disclosure of Fair Value of Financial Instruments [Line Items]
Assets	¥ 17,280	¥ 0