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Earnings Per Share (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified |
3 Months Ended | 12 Months Ended | |||||||||
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Dec. 31, 2014
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Sep. 30, 2014
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Jun. 30, 2014
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Mar. 31, 2014
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Dec. 31, 2013
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Sep. 30, 2013
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Jun. 30, 2013
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Mar. 31, 2013
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Earnings Per Share Details [Abstract] | |||||||||||
| Net income | $ 1,431us-gaap_NetIncomeLoss | $ 1,370us-gaap_NetIncomeLoss | $ 1,291us-gaap_NetIncomeLoss | $ 1,088us-gaap_NetIncomeLoss | $ 1,174us-gaap_NetIncomeLoss | $ 1,151us-gaap_NetIncomeLoss | $ 1,106us-gaap_NetIncomeLoss | $ 957us-gaap_NetIncomeLoss | $ 5,180us-gaap_NetIncomeLoss | $ 4,388us-gaap_NetIncomeLoss | $ 3,943us-gaap_NetIncomeLoss |
| Weighted-Average Number Of Shares Outstanding [Abstract] | |||||||||||
| Basic | 897.1us-gaap_WeightedAverageNumberOfSharesOutstandingBasic | 926.5us-gaap_WeightedAverageNumberOfSharesOutstandingBasic | 946.2us-gaap_WeightedAverageNumberOfSharesOutstandingBasic | ||||||||
| Dilutive effect of stock options | 2.1unp_WeightedAverageNumberOfSharesOutstandingDilutiveEffectOfStockOptions | 2.4unp_WeightedAverageNumberOfSharesOutstandingDilutiveEffectOfStockOptions | 3.6unp_WeightedAverageNumberOfSharesOutstandingDilutiveEffectOfStockOptions | ||||||||
| Dilutive effect of retention shares and units | 1.9unp_WeightedAverageNumberOfSharesOutstandingDilutiveEffectOfRetentionSharesAndUnits | 2.6unp_WeightedAverageNumberOfSharesOutstandingDilutiveEffectOfRetentionSharesAndUnits | 3.1unp_WeightedAverageNumberOfSharesOutstandingDilutiveEffectOfRetentionSharesAndUnits | ||||||||
| Diluted | 901.1us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding | 931.5us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding | 952.9us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding | ||||||||
| Earnings per share - basic | $ 1.62us-gaap_EarningsPerShareBasic | $ 1.53us-gaap_EarningsPerShareBasic | $ 1.43us-gaap_EarningsPerShareBasic | $ 1.20us-gaap_EarningsPerShareBasic | $ 1.28us-gaap_EarningsPerShareBasic | $ 1.25us-gaap_EarningsPerShareBasic | $ 1.19us-gaap_EarningsPerShareBasic | $ 1.02us-gaap_EarningsPerShareBasic | $ 5.77us-gaap_EarningsPerShareBasic | $ 4.74us-gaap_EarningsPerShareBasic | $ 4.17us-gaap_EarningsPerShareBasic |
| Earnings per share - diluted | $ 1.61us-gaap_EarningsPerShareDiluted | $ 1.53us-gaap_EarningsPerShareDiluted | $ 1.43us-gaap_EarningsPerShareDiluted | $ 1.19us-gaap_EarningsPerShareDiluted | $ 1.27us-gaap_EarningsPerShareDiluted | $ 1.24us-gaap_EarningsPerShareDiluted | $ 1.18us-gaap_EarningsPerShareDiluted | $ 1.02us-gaap_EarningsPerShareDiluted | $ 5.75us-gaap_EarningsPerShareDiluted | $ 4.71us-gaap_EarningsPerShareDiluted | $ 4.14us-gaap_EarningsPerShareDiluted |
| Stock options excluded as their inclusion would be antidilutive | 0.4us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount | 0.5us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount | 1.1us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount | ||||||||
| X | ||||||||||
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- Definition
Aggregate awards of retention and performance retention shares issued to an employee under a share-based compensation arrangement are considered options for purposes of computing diluted earnings per share. Such share-based awards shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their exercise may be contingent upon vesting. Those share-based awards are included in the diluted Earnings Per Share (EPS) computation even if the employee may not receive (or be able to sell) the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of share-based compensation arrangements shall be computed using the treasury stock method. If the equity share options or other equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding. No definition available.
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- Definition
Aggregate awards of share options issued to an employee under a share-based compensation arrangement are considered options for purposes of computing diluted earnings per share. Such share-based awards shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their exercise may be contingent upon vesting. Those share-based awards are included in the diluted Earnings Per Share (EPS) computation even if the employee may not receive (or be able to sell) the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of share-based compensation arrangements shall be computed using the treasury stock method. If the equity share options or other equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding. No definition available.
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- Definition
Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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