ACQUISITIONS AND GOODWILL - Movement of goodwill (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Movement of goodwill
Balance at the beginning of the year	¥ 2,596,393	¥ 1,905,840
Addition during the year	4,463,504	746,015
Measurement period adjustments	16,608	(55,462)
Balance at end of year	¥ 7,076,505	¥ 2,596,393

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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