Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation (Stock Option Activity) (Details)

v2.4.1.9
Stock Based Compensation (Stock Option Activity) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Jan. 31, 2015
Share-based Compensation [Abstract]  
Outstanding, beginning of period, shares 23,313,600us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Outstanding, beginning of period, weighted average exercise price $ 32.02us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Granted, shares 3,296,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Granted, weighted average exercise price $ 58.92us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Canceled or forfeited, shares (468,400)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Canceled or forfeited, weighted average exercise price $ 41.10us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
Exercised, shares (6,462,400)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Exercised, weighted average exercise price $ 30.98us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Outstanding, end of period, shares 19,678,800us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Outstanding, end of period, weighted average exercise price $ 36.65us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Exercisable, end of period, shares 11,405,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
Exercisable, end of period, weighted average exercise price $ 30.06us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
Exercisable, end of period, weighted average remaining contractual life (years) 4 years
Exercisable, end of period, aggregate intrinsic value $ 386us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Options expected to vest, shares 7,280,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber
Options expected to vest, weighted average exercise price $ 45.73us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
Options expected to vest, weighted average remaining contractual life (years) 8 years 1 month 6 days
Options expected to vest, aggregate intrinsic value $ 132us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue