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Income Taxes (Details 5) (USD $)
In Millions, unless otherwise specified |
12 Months Ended | ||
|---|---|---|---|
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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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| Interest And Penalties - Income Tax Expense [Abstract] | |||
| Total accrued liabilities for interest and penalties | $ 6us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued | $ 6us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued | |
| Total interest and penalties recognized as part of income tax expense | 9us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense | 7us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense | |
| Total interest and penalties recognized as part of income tax benefit | (4)unp_IncomeTaxExaminationPenaltiesAndInterestExpenseBenefit | ||
| Tax refund in connection to settlement | 8us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority | ||
| Taxes paid in connection to settlement | $ 11unp_IncomeTaxExaminationTaxPaidFromSettlementWithTaxingAuthority | ||
| X | ||||||||||
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- Definition
The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations. No definition available.
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| X | ||||||||||
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- Definition
The amount of tax paid upon settlement of an audit with a taxing authority. No definition available.
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| X | ||||||||||
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- Definition
The amount of the additional liability or refund received or expected based on a final settlement with a taxing authority. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The amount of estimated penalties and interest accrued as of the balance sheet date arising from income tax examinations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Details
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