CONTRACT LIABILITIES - Narrative (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Contract Liabilities [Line Items]
Revenue from contract liabilities	¥ 211,219,000	¥ 455,328,000
Advances Received From Customers [Member]
Contract Liabilities [Line Items]
Revenue from contract liabilities	182,873,000	435,213,000
Frequent Traveller Program [Member]
Contract Liabilities [Line Items]
Revenue from contract liabilities	¥ 28,346,000	¥ 20,115,443

The amount of revenue that was included in the contract liability balance at the beginning of the period. [Refer: Contract liabilities; Revenue from contracts with customers]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2021-01-01
-Paragraph 116
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2021-en-r&anchor=para_116_b&doctype=Standard
-URIDate 2021-03-24

Name:	ifrs-full_RevenueThatWasIncludedInContractLiabilityBalanceAtBeginningOfPeriod
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration