XML 127 R113.htm IDEA: XBRL DOCUMENT v3.8.0.1
Post-Employment and Other Non-Current Employee Benefits - Balances of Liabilities for Summary of Variable Return Financial Instruments Recorded at Market Values (Detail)
Dec. 31, 2017
Dec. 31, 2016
Variable return:    
Fixed and variable trust assets 100.00% 100.00%
Trading equity securities [member]    
Fixed return:    
Fixed return 14.00% 24.00%
Life annuities [member]    
Fixed return:    
Fixed return 12.00% 18.00%
Bank instruments [member]    
Fixed return:    
Fixed return 6.00% 1.00%
Federal government instruments [member]    
Fixed return:    
Fixed return 50.00% 39.00%
Publicly traded shares [member]    
Variable return:    
Variable return 18.00% 18.00%