Contract liabilities - Revenue expected to be recognized in the future (Details) ¥ in Thousands	Dec. 31, 2022 CNY (¥)
Contract liabilities
2023	¥ 321,373
2024	148,155
2025	96,651
2026	36,835
2027	322
2028	¥ 187

Amount of revenue expected to be recognized in the year five related to remaining performance obligations that are unsatisfied.

No definition available.

Name:	exc_RevenueRemainingPerformanceObligationExpectedToBeRecognizedInYearFive
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of revenue expected to be recognized in the year four related to remaining performance obligations that are unsatisfied.

No definition available.

Name:	exc_RevenueRemainingPerformanceObligationExpectedToBeRecognizedInYearFour
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of revenue expected to be recognized in the year seven related to remaining performance obligations that are unsatisfied.

No definition available.

Name:	exc_RevenueRemainingPerformanceObligationExpectedToBeRecognizedInYearSeven
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of revenue expected to be recognized in the year six related to remaining performance obligations that are unsatisfied.

No definition available.

Name:	exc_RevenueRemainingPerformanceObligationExpectedToBeRecognizedInYearSix
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of revenue expected to be recognized in the year three related to remaining performance obligations that are unsatisfied.

No definition available.

Name:	exc_RevenueRemainingPerformanceObligationExpectedToBeRecognizedInYearThree
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of revenue expected to be recognized in the year two related to remaining performance obligations that are unsatisfied.

No definition available.

Name:	exc_RevenueRemainingPerformanceObligationExpectedToBeRecognizedInYearTwo
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

No definition available.

Name:	us-gaap_ContractWithCustomerLiabilityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration