v3.3.1.900
EQUITY - CUMULATIVE CONVERTIBEL PERPETUAL PREFERENCE SHARES (DETAILS)
$ / shares in Units, $ in Millions
 12 Months Ended
Dec. 31, 2015
USD ($)
$ / shares
shares
Dec. 31, 2014
USD ($)
$ / shares
shares
Dec. 31, 2013
USD ($)
Equity Disclosures      
Preferred Stock, Shares Outstanding | shares 6,900,000 6,900,000  
Preferred Stock, Par or Stated Value Per Share $ 0.01 $ 0.01  
Preferred Stock, Liquidation Preference Per Share $ 100 $ 100  
Dividends, Preferred Stock, Cash | $ $ 34 $ 34 $ 34
Convertible perpetual preference shares      
Equity Disclosures      
Preferred Stock, Shares Outstanding | shares 6,900,000    
Preferred Stock, Par or Stated Value Per Share $ 0.01    
Preferred Stock, Liquidation Preference Per Share $ 100    
Convertible preference share, common shares issued upon conversion, at any time before mandatory conversion date 1.1331    
Convertible preference shares accrued dividends (as a percent) 4.875%    
Accumulated unpaid dividends up to a maximum additional (in dollars per share) $ 25    
Conversion price, convertible preference share (in dollars per share) $ 88.2501    
Convertible preference shares, aggregate common shares issued if converted at current conversion rate | shares 7,818,390    
Target ratio of closing share price to conversion price as a condition for conversion or redemption of Convertible Notes (as a percent) 130.00%    
Minimum | Convertible perpetual preference shares      
Equity Disclosures      
The consecutive trading days which must occur to trigger the conversion of the notes 20 days    
Maximum | Convertible perpetual preference shares      
Equity Disclosures      
The consecutive trading days which must occur to trigger the conversion of the notes 30 days