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Provisions - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2019
Bottom of range [member] | Provisions for lease restoration [Member]  
Disclosure of Provisions [line items]  
Cash outflows for existing provisions expected period 1 year
Bottom of range [member] | Provision For Claims [member]  
Disclosure of Provisions [line items]  
Cash outflows for existing provisions expected period 1 year
Top of range [member] | Provisions for lease restoration [Member]  
Disclosure of Provisions [line items]  
Cash outflows for existing provisions expected period 14 years
Top of range [member] | Provision For Claims [member]  
Disclosure of Provisions [line items]  
Cash outflows for existing provisions expected period 5 years