unp:AccountingPronouncementsAbstract Accounting Pronouncements Abstract 0 unp:AccountsPayableAndOtherCurrentLiabilitiesAbstract Accounts Payable And Other Current Liabilities Abstract 0 unp:BasisOfPresentationAbstract Basis of Presentation Abstract 0 unp:CashPaidRefundedForAbstract Cash paid during the year for: 0 unp:CommitmentsAndContingenciesAbstract Commitments And Contingencies Abstract 0 unp:CommonClassATreasuryMember Treasury Stock (units) Company common shares that have been repurchased by the entity. 0 unp:ComprehensiveIncomeLossAbstract Comprehensive Income (Loss) Abstract 0 unp:ConsolidatedStatementsOfFinancialPositionParentheticalsAbstract Consolidated Statements of Financial Position Parentheticals Abstract 0 unp:DebtAbstract Debt Abstract 0 unp:DescriptionOfNewAccountingPronouncementsNotYetAdoptedTextBlock Description of new accounting pronouncements not yet adopted text block This element is used as a single block of text to encapsulate the entire disclosure for new accounting pronouncement that has been issued but not yet adopted. 1 unp:DocumentAndEntityInformationAbstract Document and Entity Information Abstract 0 unp:EarningsPerShareDisclosureAbstract Earnings Per Share Disclosure Abstract 0 unp:EquipmentAndOtherRents Equipment and other rents Rent paid for freight cars owned by other railroads or private companies, net of rents received, incuding lease expenses primarily for locomotives, railcars, containers and trailers, office and other rentals. 3 unp:FairValueMeasurements Fair Value Measurements: 0 unp:FinancialInstrumentsAbstract Financial Instruments Abstract 0 unp:IncomeTaxesAbstract Income Taxes Abstract 0 unp:IncreaseDecreaseInMaterialAndSupplies Increase decrease in material and supplies The net change during the reporting period in the aggregate value of all materials and supplies held by the reporting entity, associated with underlying transactions that are classified as operating activities. 3 unp:MaterialsAndSupplies Materials and supplies Aggregate carrying amount, as of the balance sheet date, of unapplied materials and supplies to be used in the performance or support of carrier operations. 2 unp:NatureOfOperationsAbstract Nature of Operations Abstract 0 unp:OperationsAndSegmentationAbstract Operations and Segmentation Abstract 0 unp:OtherIncomeAbstract Other Income Abstract 0 unp:PaymentsToAcquirePropertyPlantAndEquipmentPendingFinancing Payments to acquire property plant and equipment pending financing The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; and are pending financing 3 unp:ProceedsFromLongTermCapitalObligations Proceeds from long term capital obligations ProceedsFromLongTermCapitalObligations 0 unp:ProceedsFromSaleOfAssetsFinanced Proceeds from sale of assets financed The cash inflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; and are pending financing 3 unp:PropertiesAbstract Properties Abstract 0 unp:PurchasedServicesAndMaterial Purchased Services And Material Materials and contracted services to maintain infrastructure and equipment and terminal services at intermodal and automotive facilities. 3 unp:RepurchaseOfCommonStockNotYetPaid Repurchase of common stock not yet paid Reacquire common stock during the period but not yet paid 3 unp:RetirementPlansAbstract Retirement Plans Abstract 0 unp:ScheduleOfValuationAndQualifyingAccountsAbstract Schedule Of Valuation And Qualifying Accounts Abstract 0 unp:ShareRepurchaseProgramAbstract Share Repurchase Program Abstract 0 unp:ShareRepurchaseProgramTextBlock Share Repurchase Program Text Block This element is used to disclose the repurchase of common stock through the company's repurchase program 1 unp:SignificantAccountingPoliciesAbstract Significant Accounting Policies Abstract 0 unp:StockOptionsAndOtherStockPlansAbstract Stock Options and Other Stock Plans Abstract 0 unp:StockSplitAbstract Stock Split Abstract 0 unp:StockSplitTextBlock Stock Split Text Block This element is used as a single block of text to encapsulate the entire stock split disclosure. 1