v2.4.1.9
Stock Incentive Plans (Narrative) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Length of time options exercisable, years 10 years    
Shares available for future awards 4,208,558us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant    
Allocated Share-based Compensation Expense $ 48us-gaap_AllocatedShareBasedCompensationExpense $ 36us-gaap_AllocatedShareBasedCompensationExpense $ 25us-gaap_AllocatedShareBasedCompensationExpense
Income tax benefit recognized 17us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 8us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 9us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Fair value of restricted stock and restricted stock units 82us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue 49us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue 39us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
Unrecognized compensation cost related to non-vested share $ 145us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized    
Weighted-average period 1 year 10 months 15 days    
Employee stock purchase plan issued 76,088us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans 84,168us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans 95,226us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Stock Options [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, years 3 years    
Stock Options [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, years 5 years    
Restricted Stock Units Awards [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, years 1 year    
Restricted Stock Units Awards [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options vesting period, years 10 years