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Equity - Treasury Stock - Additional Information (Details) - shares
 1 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Equity        
Treasury stock as a percentage of capital, held by parent     0.50% 0.60%
Treasury stock | Class B, Preference shares        
Equity        
Treasury stock as a percentage of capital, held by parent     0.50% 0.60%
Treasury stock | Class B, Preference shares | Restricted share unit retention plan        
Equity        
Number of shares delivered to eligible employees as a compensation for the Restricted Share Unit Retention Plan 403,399 480,661