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Critical Accounting Judgments and Key Sources of Estimation Uncertainty - Additional Information (Detail) - JointOperation
 12 Months Ended
May 16, 2017
Dec. 31, 2019
Dec. 31, 2018
Disclosure Of Joint Operations [Line Items]      
Number of joint operations   2  
WRB [Member]      
Disclosure Of Joint Operations [Line Items]      
Percent of ownership in joint operations   50.00% 50.00%
FCCL [Member]      
Disclosure Of Joint Operations [Line Items]      
Percent of ownership in joint operations 50.00%