Annual report pursuant to Section 13 and 15(d)

STOCK INCENTIVE AND STOCK OPTION PLANS (Details)

v3.8.0.1
STOCK INCENTIVE AND STOCK OPTION PLANS (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized 8,500,000    
Stock options' expiration from the date of grant 10 years    
Number of shares in every even block of KESIP shares 100    
Stock options granted for every even block of 100 KESIP shares purchased by the employee 50    
Compensation expense (net of estimated forfeitures) $ 2 $ 1 $ 2
Excess tax benefit / (deficiency) associated with share-based plans 2 1 1
Total unrecognized compensation expense (net of estimated forfeitures) $ 41    
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award      
Weighted-average maximum period of recognition of total unrecognized compensation expense related to nonvested awards 2 years    
Performance Shares      
Share-based Compensation Arrangement by Share-based Payment Award      
Vesting period 3 years    
Performance Shares | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award      
Target award based on the actual ROE performance (as a percent) 0.00%    
Performance Shares | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award      
Target award based on the actual ROE performance (as a percent) 200.00%    
Restricted Shares      
Share-based Compensation Arrangement by Share-based Payment Award      
Vesting period 2 years    
Restricted shares released after two years (as a percent) 33.33%    
Restricted shares released on the grant date each year after the first two years (as a percent) 33.33%    
Employee Stock Option      
Share-based Compensation Arrangement by Share-based Payment Award      
Vesting period 3 years    
Compensation expense (net of estimated forfeitures) $ 39 $ 31 $ 22