v2.4.1.9
Stock Options and Other Stock Plans (Details 2) (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Stock Options [Member]  
Stock Option Activity [Abstract]  
Stock options, shares outstanding at January 1, 2014 7,443,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options, shares granted 989,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options, shares exercised (2,961,000)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options, shares forfeited or expired (84,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options, shares outstanding at December 31, 2014 5,387,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options, shares vested or expected to vest at December 31, 2014 5,325,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options, share options exercisable at December 31, 2014 3,350,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options weighted-average exercise price, outstanding at January 1, 2014 $ 40.07us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options weighted-average exercise price, granted $ 87.56us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options weighted-average exercise price, exercised $ 30.59us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options weighted-average exercise price, forfeited or expired $ 68.48us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options weighted-average exercise price, outstanding at December 31, 2014 $ 53.56us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options weighted-average exercise price, vested or expected to vest at December 31, 2014 $ 53.30us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options weighted-average exercise price, options exercisable at December 31, 2014 $ 40.69us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options weighted-average remaining contractual term in years, outstanding at January 1, 2014 5 years 10 months
Stock options weighted-average remaining contractual term in years, outstanding at December 31, 2014 5 years 10 months
Stock options weighted-average remaining contractual term in years, vested or expected to vest at December 31, 2014 5 years 10 months
Stock options weighted-average remaining contractual term in years, options exercisable at December 31, 2014 4 years 5 months
Stock options aggregate intrinsic value, outstanding at January 1, 2014 $ 327us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options aggregate intrinsic value, outstanding at December 31, 2014 353us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options aggregate intrinsic value, vested or expected to vest at December 31, 2014 351us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Stock options aggregate intrinsic value, options exercisable at December 31, 2014 263us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Contractual Term Stock options are granted at the closing price on the date of grant, have ten-year contractual terms
Stock options, years until vest 3 years
Stock options, subject to performance or market-based vesting conditions None
Unrecognized Compensation Expense [Abstract]  
Unrecognized compensation expense 15us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_StockOptionMember
Expected weighted average period (in years) of nonvested stock options to be recognized 1 year
Retention Awards [Member]  
Awards Activity [Abstract]  
Awards, shares nonvested at January 1, 2014 3,712,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards, shares granted 871,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards, shares vested (1,080,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards, shares forfeited (100,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards, shares nonvested at December 31, 2014 3,403,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards weighted-average grant-date fair value, nonvested at January 1, 2014 $ 49.02us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards weighted-average grant-date fair value, granted $ 88.14us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards weighted-average grant-date fair value, vested $ 31.33us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards weighted-average grant-date fair value, forfeited $ 57.82us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Awards weighted-average grant-date fair value, nonvested at December 31, 2014 $ 64.39us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Unrecognized Compensation Expense [Abstract]  
Unrecognized compensation expense 87us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= unp_RetentionAwardsMember
Expected weighted average period (in years) of nonvested stock options to be recognized 1 year 7 months
Performance Retention Awards [Member]  
Awards Activity [Abstract]  
Awards, shares nonvested at January 1, 2014 1,888,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards, shares granted 456,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards, shares vested (661,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards, shares forfeited (100,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards, shares nonvested at December 31, 2014 1,583,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards weighted-average grant-date fair value, nonvested at January 1, 2014 $ 53.70us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards weighted-average grant-date fair value, granted $ 83.06us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards weighted-average grant-date fair value, vested $ 44.94us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards weighted-average grant-date fair value, forfeited $ 61.36us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Awards weighted-average grant-date fair value, nonvested at December 31, 2014 $ 65.33us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Unrecognized Compensation Expense [Abstract]  
Unrecognized compensation expense $ 36us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= unp_PerformanceRetentionAwardsMember
Expected weighted average period (in years) of nonvested stock options to be recognized 1 year