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Financial Instruments Risks - Progress of LtSCD ratios (Detail)
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Table Of The Progress Of LtSCD Ratios [Line Items]    
LtSCD 58.10% 62.50%
Bottom of range [member]    
Table Of The Progress Of LtSCD Ratios [Line Items]    
LtSCD 52.70% 62.50%
Weighted average [member]    
Table Of The Progress Of LtSCD Ratios [Line Items]    
LtSCD 57.70% 66.60%
Top of range [member]    
Table Of The Progress Of LtSCD Ratios [Line Items]    
LtSCD 61.80% 70.00%