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ACCOUNTS RECEIVABLE AND CONTRACT ASSETS, NET - Summary of movement of allowance for uncollectible receivables (Detail) - CNY (¥)
¥ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Receivables [Abstract]      
Balance at the beginning of the year ¥ 60,679 ¥ 28,014  
Current year credit losses 49,231 144,636 ¥ 51,430
Current year write off ¥ (109,910) (111,971) (23,416)
Balance at end of the year   ¥ 60,679 ¥ 28,014