CASH AND RESTRICTED CASH (Details) - CNY (¥) ¥ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH AND RESTRICTED CASH
Cash	¥ 9,968,109	¥ 16,259,457
Restricted cash - current assets	2,014,304	86,829
Restricted cash - non-current assets	43,954	146,643
Total cash and restricted cash shown in the consolidated statements of cash flows	¥ 12,026,367	¥ 16,492,929	¥ 5,973,262	¥ 2,284,748

Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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