v2.4.1.9
Debt (Details 2) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Aggregate Debt Maturities Excluding Market Value Adjustments [Abstract]    
Debt maturities - 2015 $ 462us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths  
Debt maturities - 2016 606us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo  
Debt maturities - 2017 1,065us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree  
Debt maturities - 2018 578us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour  
Debt maturities - 2019 652us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive  
Debt maturities - thereafter 8,117us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive  
Total debt $ 11,480us-gaap_LongTermDebt $ 9,577us-gaap_LongTermDebt