Union Pacific (UNP) 10-K 9 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 02, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Document type	10-K
Document period end date	Dec. 31, 2017
Amendment flag	false
Entity registrant name	UNION PACIFIC CORP
Entity central index key	100,885
Entity current reporting status	Yes
Entity voluntary filers	No
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Entity well known seasoned issuer	Yes
Entity public float			$ 87.3
Document fiscal year focus	2,017
Document fiscal period focus	FY
Trading Symbol	unp
Entity common stock shares outstanding		779,305,276

Consolidated Statements Of Inco

Consolidated Statements Of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating revenues:
Freight revenues	$ 19,837	$ 18,601	$ 20,397
Other revenues	1,403	1,340	1,416
Total operating revenues	21,240	19,941	21,813
Operating expenses:
Compensation and benefits	4,984	4,750	5,161
Purchased services and materials	2,363	2,258	2,421
Depreciation	2,105	2,038	2,012
Fuel	1,891	1,489	2,013
Equipment and other rents	888	1,137	1,230
Other	948	997	924
Total operating expenses	13,179	12,669	13,761
Operating income	8,061	7,272	8,052
Other income (Note 7)	290	192	226
Interest expense	(719)	(698)	(622)
Income before income taxes	7,632	6,766	7,656
Income taxes (Note 8)	3,080	(2,533)	(2,884)
Net income	$ 10,712	$ 4,233	$ 4,772
Share and Per Share (Note 9):
Earnings per share - basic	$ 13.42	$ 5.09	$ 5.51
Earnings per share - diluted	$ 13.36	$ 5.07	$ 5.49
Weighted average number of shares - basic	798.4	832.4	866.2
Weighted average number of shares - diluted	801.7	835.4	869.4
Dividends declared per share	$ 2.48	$ 2.255	$ 2.20

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Comprehensive Income [Abstract]
Net income		$ 10,712	$ 4,233	$ 4,772
Other comprehensive income/(loss):
Defined benefit plans		103	(29)	58
Foreign currency translation		28	(48)	(43)
Total other comprehensive income/(loss)	[1]	131	(77)	15
Comprehensive income		$ 10,843	$ 4,156	$ 4,787
[1]	Net of deferred taxes of $(61) million, $49 million, $(8) million, and during 2017, 2016, and 2015, respectively.

Consolidated Statements Of Com4

Consolidated Statements Of Comprehensive Income (Parentheticals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Comprehensive Income [Abstract]
Deferred taxes activity other comprehensive income/(loss)	$ (61)	$ 49	$ (8)

Consolidated Statements Of Fina

Consolidated Statements Of Financial Position - USD ($) $ in Millions	Dec. 31, 2017		Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 1,275		$ 1,277
Short-term investments (Note 14)	90		60
Accounts receivable, net (Note 11)	1,493		1,258
Materials and supplies	749		717
Other current assets	399		284
Total current assets	4,006		3,596
Investments	1,809		1,457
Net properties (Note 12)	51,605		50,389
Other assets	386		276
Total assets	57,806		55,718
Current liabilities:
Accounts payable and other current liabilities (Note 13)	3,139		2,882
Debt due within one year (Note 15)	800		758
Total current liabilities	3,939		3,640
Debt due after one year (Note 15)	16,144		14,249
Deferred income taxes (Note 8)	10,936	[1]	15,996
Other long-term liabilities	1,931		1,901
Commitments and contingencies (Notes 17 and 18)
Total liabilities	32,950		35,786
Common shareholders' equity:
Common shares, $2.50 par value, 1,400,000,000 authorized; 1,111,371,304 and 1,110,986,415 issued; 780,917,756 and 815,824,413 outstanding, respectively	2,778		2,777
Paid-in-surplus	4,476		4,421
Retained earnings	41,317		32,587
Treasury stock	(22,574)		(18,581)
Accumulated other comprehensive loss (Note 10)	(1,141)		(1,272)
Total common shareholders' equity	24,856		19,932
Total liabilities and common shareholders' equity	$ 57,806		$ 55,718
[1]	2017 amounts reflect the provisional impact of the Tax Act.

Consolidated Statements Of Fin6

Consolidated Statements Of Financial Position (Parentheticals) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Consolidated Statements Of Financial Position [Abstract]
Common shares, par value	$ 2.50	$ 2.50
Common shares authorized	1,400,000,000	1,400,000,000
Common shares issued	1,111,371,304	1,110,986,415
Common shares outstanding	780,917,756	815,824,413

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities
Net income	$ 10,712	$ 4,233	$ 4,772
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	2,105	2,038	2,012
Deferred and other income taxes	(5,067)	831	765
Net gain on non-operating asset dispositions	(111)	(94)	(144)
Other operating activities, net	(282)	(228)	116
Changes in current assets and liabilities:
Accounts receivable, net	(235)	98	255
Materials and supplies	(32)	19	(24)
Other current assets	9	22	(47)
Accounts payable and other current liabilities	182	232	(276)
Income and other taxes	(51)	374	(85)
Cash provided by operating activities	7,230	7,525	7,344
Investing Activities
Capital investments	(3,238)	(3,505)	(4,650)
Proceeds from asset sales	168	129	251
Purchases of short-term investments (Note 14)	(120)	(580)
Maturities of short-term investments (Note 14)	90	520
Other investing activities, net	14	43	(77)
Cash used in investing activities	(3,086)	(3,393)	(4,476)
Financing Activities
Common share repurchases (Note 19)	(4,013)	(3,105)	(3,465)
Debt issued	2,735	1,983	3,328
Dividends paid	(1,982)	(1,879)	(2,344)
Debt repaid	(840)	(1,013)	(556)
Debt exchange		(191)
Other financing activities, net	(46)	(41)	(26)
Cash used in financing activities	(4,146)	(4,246)	(3,063)
Net change in cash and cash equivalents	(2)	(114)	(195)
Cash and cash equivalents at beginning of year	1,277	1,391	1,586
Cash and cash equivalents at end of year	1,275	1,277	1,391
Non-cash investing and financing activities:
Capital investments accrued but not yet paid	366	223	100
Capital lease financings	19		13
Cash paid during the year for:
Income taxes, net of refunds	(2,112)	(1,347)	(2,156)
Interest, net of amounts capitalized	$ (666)	$ (652)	$ (592)

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Common Shareholders' Equity - USD ($) $ in Millions	Common Shares [Member]	Paid-in-Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	AOCI [Member]	[1]	Total
Shareholders' equity, beginning balance at Dec. 31, 2014	$ 2,775	$ 4,321	$ 27,367	$ (12,064)	$ (1,210)		$ 21,189
Common shares, beginning balance at Dec. 31, 2014	1,110,100,000			(226,700,000)
Net income			4,772				4,772
Other comp. income/(loss)					15		15	[2]
Conversion, stock option exercises, forfeitures, and other	$ 1	96					97
Conversion, stock option exercises, forfeitures, and other (shares)	300,000			800,000
Share repurchases (Note 19)				$ (3,465)			(3,465)
Share repurchases (Note 19) (shares)				(35,300,000)
Cash dividends declared			(1,906)				(1,906)
Shareholders' equity, ending balance at Dec. 31, 2015	$ 2,776	4,417	30,233	$ (15,529)	(1,195)		20,702
Common shares, ending balance at Dec. 31, 2015	1,110,400,000			(261,200,000)
Net income			4,233				4,233
Other comp. income/(loss)					(77)		(77)	[2]
Conversion, stock option exercises, forfeitures, and other	$ 1	4		$ 53			58
Conversion, stock option exercises, forfeitures, and other (shares)	600,000			1,100,000
Share repurchases (Note 19)				$ (3,105)			$ (3,105)
Share repurchases (Note 19) (shares)				(35,100,000)			(35,055,187)
Cash dividends declared			(1,879)				$ (1,879)
Shareholders' equity, ending balance at Dec. 31, 2016	$ 2,777	4,421	32,587	$ (18,581)	(1,272)		$ 19,932
Common shares, ending balance at Dec. 31, 2016	1,111,000,000			(295,200,000)			815,824,413
Net income			10,712				$ 10,712
Other comp. income/(loss)					131		131	[2]
Conversion, stock option exercises, forfeitures, and other	$ 1	55		$ 20			76
Conversion, stock option exercises, forfeitures, and other (shares)	400,000			1,100,000
Share repurchases (Note 19)				$ (4,013)			$ (4,013)
Share repurchases (Note 19) (shares)				(36,400,000)			(36,352,848)
Cash dividends declared			(1,982)				$ (1,982)
Shareholders' equity, ending balance at Dec. 31, 2017	$ 2,778	$ 4,476	$ 41,317	$ (22,574)	$ (1,141)		$ 24,856
Common shares, ending balance at Dec. 31, 2017	1,111,400,000			(330,500,000)			780,917,756
[1]	AOCI = Accumulated Other Comprehensive Income/(Loss) (Note 10)
[2]	Net of deferred taxes of $(61) million, $49 million, $(8) million, and during 2017, 2016, and 2015, respectively.

Consolidated Statements of Cha9

Consolidated Statements of Changes in Common Shareholders' Equity (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements Of Changes In Common Shareholders' Equity [Abstract]
Cash dividends declared per share	$ 2.48	$ 2.255	$ 2.20

Nature Of Operations

Nature Of Operations	12 Months Ended
	Dec. 31, 2017
Nature Of Operations [Abstract]
Nature of Operations	For purposes of this report, unless the context otherwise requires, all references herein to the “Corporation”, “Company”, “UPC”, “we”, “us”, and “our” mean Union Pacific Corporation and its subsidiaries, including Union Pacific Railroad Company, which will be separately referred to herein as “UPRR” or the “Railroad”. 1. Nature of Operations  Operations and Segmentation – We are a Class I railroad operating in the U.S. Our network includes 32,122 route miles, linking Pacific Coast and Gulf Coast ports with the Midwest and Eastern U.S. gateways and providing several corridors to key Mexican gateways. We own 26,042 miles and operate on the remainder pursuant to trackage rights or leases. We serve the western two-thirds of the country and maintain coordinated schedules with other rail carriers for the handling of freight to and from the Atlantic Coast, the Pacific Coast, the Southeast, the Southwest, Canada, and Mexico. Export and import traffic is moved through Gulf Coast and Pacific Coast ports and across the Mexican and Canadian borders.  The Railroad, along with its subsidiaries and rail affiliates, is our one reportable operating segment. Although we provide and analyze revenue by commodity group, we treat the financial results of the Railroad as one segment due to the integrated nature of our rail network. The following table provides freight revenue by commodity group:      Millions 2017 2016 2015  Agricultural Products $ 3,685 $ 3,625 $ 3,581  Automotive 1,998 2,000 2,154  Chemicals 3,596 3,474 3,543  Coal 2,645 2,440 3,237  Industrial Products 4,078 3,348 3,808  Intermodal 3,835 3,714 4,074  Total freight revenues $ 19,837 $ 18,601 $ 20,397  Other revenues 1,403 1,340 1,416  Total operating revenues $ 21,240 $ 19,941 $ 21,813  Although our revenues are principally derived from customers domiciled in the U.S., the ultimate points of origination or destination for some products we transport are outside the U.S. Each of our commodity groups includes revenue from shipments to and from Mexico. Included in the above table are freight revenues from our Mexico business which amounted to $ 2.3 billion in 2017, $2.2 billion in 201 6 , and $2.2 billion in 201 5 .  Basis of Presentation – The Consolidated Financial Statements are presented in accordance with accounting principles generally accepted in the U.S. (GAAP) as codified in the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC).

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Significant Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies  Principles of Consolidation – The Consolidated Financial Statements include the accounts of Union Pacific Corporation and all of its subsidiaries. Investments in affiliated companies (20% to 50% owned) are accounted for using the equity method of accounting. All intercompany transactions are eliminated. We currently have no less than majority-owned investments that require consolidation under variable interest entity requirements.  Cash and Cash Equivalents – Cash equivalents consist of investments with original maturities of three months or less.  Accounts Receivable – Accounts receivable includes receivables reduced by an allowance for doubtful accounts. The allowance is based upon historical losses, credit worthiness of customers, and current economic conditions. Receivables not expected to be collected in one year and the associated allowances are classified as other assets in our Consolidated Statements of Financial Position.  Investments – Investments represent our investments in affiliated companies (20% to 50% owned) that are accounted for under the equity method of accounting and investments in companies (less than 20% owned) accounted for under the cost method of accounting. The results of operations for our equity method investments that are integral to our operations are recorded in operating expenses.  Materials and Supplies – Materials and supplies are carried at the lower of average cost or market.  Property and Depreciation – Properties and equipment are carried at cost and are depreciated on a straight-line basis over their estimated service lives, which are measured in years, except for rail in high-density traffic corridors (i.e., all rail lines except for those subject to abandonment, yard and switching tracks, and electronic yards), for which lives are measured in millions of gross tons per mile of track. We use the group method of depreciation in which all items with similar characteristics, use, and expected lives are grouped together in asset classes, and are depreciated using composite depreciation rates. The group method of depreciation treats each asset class as a pool of resources, not as singular items. We determine the estimated service lives of depreciable railroad assets by means of depreciation studies. Under the group method of depreciation, no gain or loss is recognized when depreciable property is retired or replaced in the ordinary course of business.  Impairment of Long-lived Assets – We review long-lived assets, including identifiable intangibles, for impairment when events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If impairment indicators are present and the estimated future undiscounted cash flows are less than the carrying value of the long-lived assets, the carrying value is reduced to the estimated fair value as measured by the discounted cash flows.  Revenue Recognition – We recognize freight revenues as freight moves from origin to destination. The allocation of revenue between reporting periods is based on the relative transit time in each reporting period with expenses recognized as incurred. Other revenues, which include revenues earned by our subsidiaries, revenues from our commuter rail operations, and accessorial revenue, are recognized as service is performed or contractual obligations are met. Customer incentives, which are primarily provided for shipping a specified cumulative volume or shipping to/from specific locations, are recorded as a reduction to operating revenues based on actual or projected future customer shipments.  Translation of Foreign Currency – Our portion of the assets and liabilities related to foreign investments are translated into U.S. dollars at the exchange rates in effect at the balance sheet date. Revenue and expenses are translated at the average rates of exchange prevailing during the year. Unrealized gains or losses are reflected within common shareholders’ equity as accumulated other comprehensive income or loss.  Fair Value Measurements – We use a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The level in the fair value hierarchy within which the fair value measurement in its entirety falls is determined based on the lowest level input that is significant to the fair value measurement in its entirety. These levels include:  Level 1: Quoted market prices in active markets for identical assets or liabilities. Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data. Level 3: Unobservable inputs that are not corroborated by market data.  We have applied fair value measurements to our short term investments, pension plan assets and short- and long-term debt.  Stock-Based Compensation – We have several stock-based compensation plans under which employees and non-employee directors receive stock options, nonvested retention shares, and nonvested stock units. We refer to the nonvested shares and stock units collectively as “retention awards”. We have elected to issue treasury shares to cover option exercises and stock unit vestings, while new shares are issued when retention shares are granted.  We measure and recognize compensation expense for all stock-based awards made to employees and directors, including stock options. Compensation expense is based on the calculated fair value of the awards as measured at the grant date and is expensed ratably over the service period of the awards (generally the vesting period). The fair value of retention awards is the closing stock price on the date of grant, while the fair value of stock options is determined by using the Black-Scholes option pricing model.  Earnings Per Share – Basic earnings per share are calculated on the weighted-average number of common shares outstanding during each period. Diluted earnings per share include shares issuable upon exercise of outstanding stock options and stock-based awards where the conversion of such instruments would be dilutive.  Income Taxes – We account for income taxes by recording taxes payable or refundable for the current year and deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in our financial statements or tax returns. These expected future tax consequences are measured based on current tax law; the effects of future tax legislation are not anticipated. Future tax legislation, such as a change in the corporate tax rate, could have a material impact on our financial condition, results of operations, or liquidity.  When appropriate, we record a valuation allowance against deferred tax assets to reflect that these tax assets may not be realized. In determining whether a valuation allowance is appropriate, we consider whether it is more likely than not that all or some portion of our deferred tax assets will not be realized, based on management’s judgments using available evidence for purposes of estimating whether future taxable income will be sufficient to realize a deferred tax asset.  We recognize tax benefits that are more likely than not to be sustained upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50 percent likely to be realized upon settlement. A liability for “unrecognized tax benefits” is recorded for any tax benefits claimed in our tax returns that do not meet these recognition and measurement standards.  Pension and Postretirement Benefits – We incur certain employment-related expenses associated with pensions and postretirement health benefits. In order to measure the expense associated with these benefits, we must make various assumptions including discount rates used to value certain liabilities, expected return on plan assets used to fund these expenses, compensation increases, employee turnover rates, anticipated mortality rates, and expected future health care costs. The assumptions used by us are based on our historical experience as well as current facts and circumstances. We use an actuarial analysis to measure the expense and liability associated with these benefits.  Personal Injury – The cost of injuries to employees and others on our property is charged to expense based on estimates of the ultimate cost and number of incidents each year. We use an actuarial analysis to measure the expense and liability. Our personal injury liability is not discounted to present value. Legal fees and incidental costs are expensed as incurred.  Asbestos – We estimate a liability for asserted and unasserted asbestos-related claims based on an assessment of the number and value of those claims. We use a statistical analysis to assist us in properly measuring our potential liability. Our liability for asbestos-related claims is not discounted to present value due to the uncertainty surrounding the timing of future payments. Legal fees and incidental costs are expensed as incurred.  Environmental – When environmental issues have been identified with respect to property currently or formerly owned, leased, or otherwise used in the conduct of our business, we perform, with the assistance of our consultants, environmental assessments on such property. We expense the cost of the assessments as incurred. We accrue the cost of remediation where our obligation is probable and such costs can be reasonably estimated. We do not discount our environmental liabilities when the timing of the anticipated cash payments is not fixed or readily determinable. Legal fees and incidental costs are expensed as incurred.  Use of Estimates – The preparation of our Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect certain reported assets and liabilities, and the disclosure of certain contingent assets and liabilities as of the date of the consolidated financial statements, as well as the reported amounts of revenue and expenses during the reporting period . Actual future results may differ from such estimates.

Accounting Pronouncements

Accounting Pronouncements	12 Months Ended
	Dec. 31, 2017
Accounting Pronouncements [Abstract]
Accounting Pronouncements	3. Accounting Pronouncements  In May 2014, the FASB issued Accounting Standards Update No. 2014-09 (ASU 2014-09), Revenue from Contracts with Customers (Topic 606) . ASU 2014-09 supersedes the revenue recognition guidance in Topic 605, Revenue Recognition. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods and services to customers in an amount that reflects the consideration to which the entity expects to be entitled in the exchange for t hose goods or services. This may require the use of more judgment and estimates in order to correctly recognize the revenue expected as an outcome of each specific performance obligation. Additionally, this guidance will require the disclosure of the nature, amount, and timing of revenue arising from contracts so as to aid in the understanding of the users of financial statements.  This standard is effective for annual reporting periods beginning after December 15, 2017. The Company has analyzed our freight and other revenues and we expect to continue to recognize freight revenues as freight moves from origin to destination and to recognize other revenues as identified performance obligations are satisfied. We have also analyzed freight and other revenues in the context of the new guidance on principal versus agent considerations and evaluated the required new disclosures. Effective January 1, 2018, the Company adopted ASU 2014-09 using the modified retrospective transition method. The ASU did not have an impact on our consolidated financial position, results of operations, or cash flows .  In January 2016, the FASB issued Accounting Standards Update No. 2016-01 (ASU 2016-01), Recognition and Measurement of Financial Assets and Financial Liabilities (Subtopic 825-10) . ASU 2016-01 provides guidance for the recognition, measurement, presentation, and disclosure of financial instruments. This guidance is effective for annual and interim periods beginning after December 15, 2017, and early adoption is not permitted. ASU 2016-01 is not expected to have a material impact on our consolidated financial position, results of operations, or cash flows.  In March 2017, the FASB issued Accounting Standards Update No. 2017-07 (ASU 2017-07), Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (Topic 715) . ASU 2017-07 requires the service cost component be reported separately from the other components of net benefit costs in the income statement, provides explicit guidance on the presentation of the service cost component and the other components of net benefit cost in the income statement, and allows only the service cost component of net benefit cost to be eligible for capitalization. This standard is effective for annual and interim reporting periods beginning after December 15, 2017, and we intend to adopt the standard beginning in 2018 using retrospective adoption. The Company currently records service costs and net benefit costs within compensation and benefits expense. Upon adoption, the service cost will be recorded within compensation and benefits expense, and the other components of net benefit costs, including $69 million related to the 2017 workforce reduction plan as described in Note 4, will be recorded in other income. The retrospective impact of future adoption is shown in the table below:     Millions 2017 2016 2015  Increase/(decrease) in operating income $ 45 $ (29) $ 30  Increase/(decrease) in other income (45) 29 (30)  In February 2016, the FASB issued Accounting Standards Update No. 2016-02 (ASU 2016-02), Leases (Subtopic 842) . ASU 2016-02 will require companies to recognize lease assets and lease liabilities on the balance sheet and disclose key information about leasing arrangements. For public companies, this standard is effective for annual reporting periods beginning after December 15, 2018, and early adoption is permitted. Management is currently evaluating the impact of this standard on our consolidated financial position, results of operations, and cash flows, and expects that the adoption will result in an increase in the Company’s assets and liabilities of over $2 billion.  On December 22, 2017 the SEC staff issued S taff Accounting Bulletin 118 (SAB 118) , which provides guidance on accounting for the tax effects of the Tax Cuts and Jobs Act (the “ Tax Act”). SAB 118 provides a measurement period that should not extend beyond one year from the enactment date for companies to complete the accounting under A ccounting S tandards C odification (ASC) 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Tax Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but for which they are able to determine a reasonable estimate, it must record a provisional amount in the financial statements. Provisional treatment is proper in light of anticipated additional guidance from various taxing authorities, the SEC, the FASB, and even the Joint Committee on Taxation. Provisional treatment is also necessary if the company is waiting for final financial information from domestic and foreign equity investments. If a company cannot determine a provisional amount to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act.  

Workforce Reduction Plan

Workforce Reduction Plan	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	4. Workforce Reduction Plan  On August 16, 2017, the Company approved and commenced a management and administrative personnel reorganization plan (the “Plan”) furthering its on-going efforts to increase efficiency and more effectively align Company resources. The Plan implemented productivity initiatives identified during a recently completed Company-wide organizational review that included the reduction of approximately 460 management positions and 250 agreement positions. The Plan resulted in a pretax charge recognized in the third quarter of 2017 within compensation and benefits expense in our Consolidated Statements of Income. This charge consisted of management employee termination benefits, including pension expenses, severance costs, and acceleration of equity compensation expense as shown in the table below. The actions associated with the Plan are substantially complete, and we do not expect to incur additional charges for the Plan in subsequent years.     Millions Compensation and  for the Year Ended December 31, 2017 Benefits Expense  Pension $ 69  Severance 12  Equity Compensation 5  Total $ 86 

Stock Options And Other Stock P

Stock Options And Other Stock Plans	12 Months Ended
	Dec. 31, 2017
Stock Options And Other Stock Plans [Abstract]
Stock Options and Other Stock Plans	5. Stock Options and Other Stock Plans  In April 2000, the shareholders approved the Union Pacific Corporation 2000 Directors Plan (Directors Plan) whereby 2,200,000 shares of our common stock were reserved for issuance to our non-employee directors. Under the Directors Plan, each non-employee director, upon his or her initial election to the Board of Directors, receives a grant of 4,000 retention shares or retention stock units. Prior to December 31, 2007, each non-employee director received annually an option to purchase at fair value a number of shares of our common stock, not to exceed 20,000 shares during any calendar year, determined by dividing 60,000 by 1/3 of the fair market value of one share of our common stock on the date of such Board of Directors meeting, with the resulting quotient rounded up or down to the nearest 50 shares. In September 2007, the Board of Directors eliminated the annual payment of options for 2008 and all future years. As of December 31, 2017 , 44,000 restricted shares and no options were outstanding under the Directors Plan.  The Union Pacific Corporation 2004 Stock Incentive Plan (2004 Plan) was approved by shareholders in April 2004. The 2004 Plan reserved 84,000,000 shares of our common stock for issuance, plus any shares subject to awards made under previous plans that were outstanding on April 16, 2004, and became available for regrant pursuant to the terms of the 2004 Plan. Under the 2004 Plan, non-qualified options, stock appreciation rights, retention shares, stock units, and incentive bonus awards may be granted to eligible employees of the Corporation and its subsidiaries. Non-employee directors are not eligible for awards under the 2004 Plan. As of December 31, 2017 , 1,557,350 options and 962 retention shares and stock units were outstanding under the 2004 Plan. We no longer grant any stock options or other stock or unit awards under this plan.  The Union Pacific Corporation 2013 Stock Incentive Plan (2013 Plan) was approved by shareholders in May 2013. The 2013 Plan reserved 78,000,000 shares of our common stock for issuance, plus any shares subject to awards made under previous plans as of February 28, 2013, that are subsequently cancelled, expired, forfeited or otherwise not issued under previous plans. Under the 2013 Plan, non-qualified options, incentive stock options, retention shares, stock units, and incentive bonus awards may be granted to eligible employees of the Corporation and its subsidiaries. Non-employee directors are not eligible for awards under the 2013 Plan. As of December 31, 2017 , 4,072,514 options and 3,450,600 retention shares and stock units were outstanding under the 2013 Plan. Pursuant to the above plans 72,151,415 ; 73,745,250 ; and 76,548,520 ; shares of our common stock were authorized and available for grant at December 31, 2017 , 2016, and 2015 , respectively.  Stock-Based Compensation – We have several stock-based compensation plans under which employees and non-employee directors receive stock options, nonvested retention shares, and nonvested stock units. We refer to the nonvested shares and stock units collectively as “retention awards”. We have elected to issue treasury shares to cover option exercises and stock unit vestings, while new shares are issued when retention shares are granted.  Information regarding stock-based compensation appears in the table below:      Millions 2017 2016 2015  Stock-based compensation, before tax:  Stock options $ 19 $ 16 $ 17  Retention awards 84 66 81  Total stock-based compensation, before tax $ 103 $ 82 $ 98  Excess tax benefits from equity compensation plans $ 44 $ 28 $ 62  Stock Options – We estimate the fair value of our stock option awards using the Black-Scholes option pricing model. The table below shows the annual weighted-average assumptions used for valuation purposes:      Weighted-Average Assumptions 2017 2016 2015  Risk-free interest rate 2.0% 1.3% 1.3%  Dividend yield 2.3% 2.9% 1.8%  Expected life (years) 5.3 5.1 5.1  Volatility 21.7% 23.2% 23.4%  Weighted-average grant-date fair value of options granted $ 18.19 $ 11.36 $ 22.30  The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant; the expected dividend yield is calculated as the ratio of dividends paid per share of common stock to the stock price on the date of grant; the expected life is based on historical and expected exercise behavior; and expected volatility is based on the historical volatility of our stock price over the expected life of the option.  A summary of s tock option activity during 2017 is presented below:      Options (thous.) Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (millions)  Outstanding at January 1, 2017 6,162 $ 73.13 5.9 yrs. $ 205  Granted 1,086 107.30 N/A N/A  Exercised (1,448) 56.69 N/A N/A  Forfeited or expired (170) 92.18 N/A N/A  Outstanding at December 31, 2017 5,630 $ 83.37 5.8 yrs. $ 286  Vested or expected to vest at December 31, 2017 5,607 $ 83.25 5.8 yrs. $ 285  Options exercisable at December 31, 2017 3,466 $ 75.96 4.2 yrs. $ 201  Stock options are granted at the closing price on the date of grant, have ten -year contractual terms, and vest no later than three years from the date of grant. None of the stock options outstanding at December 31, 2017 , are subject to performance or market-based vesting conditions.  At December 31, 2017 , there was $19 million of unrecognized compensation expense related to nonvested stock options, which is expected to be recognized over a weighted-average period of 1.1 years. Additional information regarding stock option exer cises appears in the following table :      Millions 2017 2016 2015  Intrinsic value of stock options exercised $ 88 $ 52 $ 50  Cash received from option exercises 59 39 27  Treasury shares repurchased for employee payroll taxes (18) (15) (12)  Tax benefit realized from option exercises 34 20 19  Aggregate grant-date fair value of stock options vested 20 19 19  Retention Awards – The fair value of retention awards is based on the closing price of the stock on the grant date. Dividends and dividend equivalents are paid to participants during the vesting periods.  Changes in our retention awards during 201 7 were as follows:      Shares (thous.) Weighted-Average Grant-Date Fair Value  Nonvested at January 1, 2017 2,789 $ 84.68  Granted 575 107.51  Vested (894) 70.91  Forfeited (157) 94.01  Nonvested at December 31, 2017 2,313 $ 95.04  Retention awards are granted at no cost to the employee or non-employee director and vest over periods lasting up to four years . At December 31, 2017 , there was $87 million of total unrecognized compensation expense related to nonvested retention awards, which is expected to be recognized over a weighted-average period of 1.6 years.  Performance Retention Awards – In February 2017 , our Board of Directors approved performance stock unit grants. The basic terms of these performance stock units are identical t o those granted in February 2016 , except for different annual return on invested cap ital (ROIC) performance targets. T he 2016 and 2017 plans also include the addition of relative operating income growth (OIG) as a modifier compared to the companies included in t he S&P 500 Industrials Index. We define ROIC as net operating profit adjusted for interest expense (including interest on the present value of operating leases) and taxes on interest divided by average invested capital adjusted for the present value of operating leases. The modifier can be up to +/- 25% of the award earned based on the ROIC achieved.  Stock units awarded to selected employees under these grants are subject to continued employment for 37 months and the attainment of certain levels of ROIC, and for the 2016 and 2017 plans, modified for the relative OIG. We expense the fair value of the units that are probable of being earned based on our forecasted ROIC over the 3 -year performance period, and with respect to the third year of the 2016 and 2017 plans, the relative OIG modifier. We measure the fair value of these performance stock units based upon the closing price of the underlying common stock as of the date of grant, reduced by the present value of estimated future dividends. Dividend equivalents are paid to participants only after the units are earned.  The assumptions used to calculate the present value of estimated future divide nds related to the February 2017 grant were as follows:      2017  Dividend per share per quarter $ 0.605  Risk-free interest rate at date of grant 1.5%  Changes in our performa nce retention awards during 2017 were as follows:      Shares (thous.) Weighted-Average Grant-Date Fair Value  Nonvested at January 1, 2017 1,145 $ 86.23  Granted 461 101.38  Vested (255) 83.06  Unearned (110) 83.06  Forfeited (103) 91.36  Nonvested at December 31, 2017 1,138 $ 92.92  At December 31, 2017 , there was $39 million of total unrecognized compensation expense related to nonvested performance retention awards, which is expected to be recognized over a weighted-average period of 1.5 years. This expense is subject to achievement of the performance measures established for the performance stock unit grants.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2017
Retirement Plans [Abstract]
Retirement Plans	6. Retirement Plans  Pension and Other Postretirement Benefits  Pension Plans – We provide defined benefit retirement income to eligible non-union employees through qualified and non-qualified (supplemental) pension plans. Qualified and non-qualified pension benefits are based on years of service and the highest compensation during the latest years of employment, with specific reductions made for early retirements. Non-union employees hired on or after January 1, 2018, are no longer eligible for pension benefits, but will be eligible for an enhanced 401(k) plan as described below in other retirement programs.  Other Postretirement Benefits (OPEB) – We provide medical and life insurance benefits for eligible retirees hired before January 1, 2004. These benefits are funded as medical claims and life insurance premiums are paid.  Funded Status  We are required by GAAP to separately recognize the overfunded or underfunded status of our pension and OPEB plans as an asset or liability. The funded status represents the difference between the projected benefit obligation (PBO) and the fair value of the plan assets. Our non-qualified (supplemental) pension plan is unfunded by design. The PBO of the pension plans is the present value of benefits earned to date by plan participants, including the effect of assumed future compensation increases. The PBO of the OPEB plan is equal to the accumulated benefit obligation, as the present value of the OPEB liabilities is not affected by compensation increases. Plan assets are measured at fair value. We use a December 31 measurement date for plan assets and obligations for all our retirement plans.  Changes in our PBO and plan assets were as follows for the years ended December 31:      Funded Status Pension OPEB  Millions 2017 2016 2017 2016  Projected Benefit Obligation  Projected benefit obligation at beginning of year $ 4,110 $ 3,958 $ 334 $ 329  Service cost 90 84 2 1  Interest cost 142 143 10 11  Plan curtailment cost 20 - (1) -  Special termination cost 49 - - -  Actuarial loss 382 124 7 16  Gross benefits paid (264) (199) (22) (23)  Projected benefit obligation at end of year $ 4,529 $ 4,110 $ 330 $ 334  Plan Assets  Fair value of plan assets at beginning of year $ 3,748 $ 3,544 $ - $ -  Actual return on plan assets 716 279 - -  Voluntary funded pension plan contributions - 100 - -  Non-qualified plan benefit contributions 24 24 22 23  Gross benefits paid (264) (199) (22) (23)  Fair value of plan assets at end of year $ 4,224 $ 3,748 $ - $ -  Funded status at end of year $ (305) $ (362) $ (330) $ (334)  Amounts recognized in the statement of financial position as of December 31, 2017, and 2016 consist of:      Pension OPEB  Millions 2017 2016 2017 2016  Noncurrent assets $ 196 $ 67 $ - $ -  Current liabilities (27) (24) (23) (24)  Noncurrent liabilities (474) (405) (307) (310)  Net amounts recognized at end of year $ (305) $ (362) $ (330) $ (334)  Pre-tax amounts recognized in accumulated other comprehensive income/(loss) as of December 31, 2017, and 2016 consist of:      2017 2016  Millions Pension OPEB Total Pension OPEB Total  Prior service cost $ - $ (1) $ (1) $ - $ (2) $ (2)  Net actuarial loss (1,533) (120) (1,653) (1,681) (123) (1,804)  Total $ (1,533) $ (121) $ (1,654) $ (1,681) $ (125) $ (1,806)  Pre-tax changes recognized in other comprehensive inco me/(loss) during 2017, 2016, and 2015 were as follows:      Pension OPEB  Millions 2017 2016 2015 2017 2016 2015  Net actuarial (loss)/gain $ 67 $ (112) $ (31) $ (6) $ (16) $ 18  Amortization of:  Prior service cost/(credit) - - - 1 (9) (10)  Actuarial loss 81 83 106 9 10 13  Total $ 148 $ (29) $ 75 $ 4 $ (15) $ 21  Amounts included in accumulated other comprehensive income/(loss) expected to be amortized into net periodic cost during 2018 :      Millions Pension OPEB Total  Prior service credit $ - $ (1) $ (1)  Net actuarial loss (90) (9) (99)  Total $ (90) $ (10) $ (100)  Underfunded Accumulated Benefit Obligation – The accumulated benefit obligation (ABO) is the present value of benefits earned to date, assuming no future compensation growth. The underfunded accumulated benefit obligation represents the difference between the ABO and the fair value of plan assets. At December 31, 2017, and 2016 , the non-qualified (supplemental) plan ABO was $481 million and $ 412 million, respectively. The following table discloses only the PBO, ABO, and fair value of plan assets for pension plans where the accumulated benefit obligation is in excess of the fair value of the plan assets as of December 31 :      Underfunded Accumulated Benefit Obligation  Millions 2017 2016  Projected benefit obligation $ 501 $ 428  Accumulated benefit obligation $ 481 $ 412  Fair value of plan assets - -  Underfunded accumulated benefit obligation $ (481) $ (412)  The ABO for all defined benefit pension plans was $4.2 billion and $3.9 billion at December 31, 2017, and 2016 , respectively.  Assumptions – The weighted-average actuarial assumptions used to determine benefit obligations at December 31:      Pension OPEB  Percentages 2017 2016 2017 2016  Discount rate 3.62% 4.20% 3.53% 4.00%  Compensation increase 4.20% 4.20% N/A N/A  Health care cost trend rate (employees under 65) N/A N/A 6.09% 6.31%  Ultimate health care cost trend rate N/A N/A 4.50% 4.50%  Year ultimate trend rate reached N/A N/A 2038 2038  Expense  Both pension and OPEB expense are determined based upon the annual service cost of benefits (the actuarial cost of benefits earned during a period) and the interest cost on those liabilities, less the expected return on plan assets. The expected long-term rate of return on plan assets is applied to a calculated value of plan assets that recognizes changes in fair value over a five -year period. This practice is intended to reduce year-to-year volatility in pension expense, but it can have the effect of delaying the recognition of differences between actual returns on assets and expected returns based on long-term rate of return assumptions. Differences in actual experience in relation to assumptions are not recognized in net income immediately, but are deferred in accumulated other comprehensive income and, if necessary, amortized as pension or OPEB expense.  The workforce reduction plan initiated in the third quarter of 2017 included a curtailment loss of $20 million and a special termination benefit of $49 million as a result of a remeasurement as of September 30, 2017, due to the eliminated future service for approximately 460 management employees. These amounts were recognized in 2017 within compensation and benefits expense in our Consolidated Statements of Income . In connection with this remeasurement, the Company also updated the pension effective discount rate assumption from 4.20% to 3.81 % .  The components of our net periodic pension and OPEB cost were as follows for the years ended December 31:      Pension OPEB  Millions 2017 2016 2015 2017 2016 2015  Net Periodic Benefit Cost:  Service cost $ 90 $ 84 $ 106 $ 2 $ 1 $ 3  Interest cost 142 143 163 10 11 13  Expected return on plan assets (267) (267) (255) - - - Plan curtailment cost 20 - - - - -  Special termination cost 49 - - - - -  Amortization of:  Prior service cost/(credit) - - - 1 (9) (10)  Actuarial loss 81 83 106 9 10 13  Net periodic benefit cost $ 115 $ 43 $ 120 $ 22 $ 13 $ 19   Assumptions – The weighted-average actuarial assumptions used to determine expense were as follows:      Pension OPEB  Percentages 2017 2016 2015 2017 2016 2015  Discount rate for benefit obligations 4.09% 4.37% 3.94% 3.89% 4.13% 3.74%  Discount rate for interest on benefit obligations 3.47% 3.65% 3.94% 3.25% 3.34% 3.74%  Discount rate for service cost 4.41% 4.69% 3.94% 4.25% 4.59% 3.74%  Discount rate for interest on service cost 4.27% 4.55% 3.94% 4.11% 4.44% 3.74%  Expected return on plan assets 7.00% 7.50% 7.50% N/A N/A N/A  Compensation increase 4.13% 4.20% 4.00% N/A N/A N/A  Health care cost trend rate (employees under 65) N/A N/A N/A 6.31% 6.52% 6.34%  Ultimate health care cost trend rate N/A N/A N/A 4.50% 4.50% 4.50%  Year ultimate trend reached N/A N/A N/A 2038 2038 2028  Beginning in 2016, we measure the service cost and interest cost components of our net periodic benefit cost by using individual spot discount rates matched with separate cash flows for each future year. The discount rates were based on a yield curve of high quality corporate bonds. The expected return on plan assets is based on our asset allocation mix and our historical return, taking into account current and expected market conditions. The actual return/(loss) on pension plan assets, net of fees, was approximately 19% in 2017, 8% in 2016 , and (1)% i n 2015.  Assumed health care cost trend rates have an effect on the expense and liabilities reported for health care plans. The assumed health care cost trend rate is based on historical rates and expected market conditions. The 2018 assumed health care cost trend rate for employees under 65 is 6.09% . It is assumed the rate will decrease gradually to an ultimate rate of 4.5% in 2038 and will remain at that level. A one-percentage point change in the assumed health care cost trend rates would have the following effects on OPEB:      Millions One % pt. Increase One % pt. Decrease  Effect on total service and interest cost components $ 1 $ (1)  Effect on accumulated benefit obligation 19 (16)  Cash Contributions  The following table details our cash contributions for the qualified pension plans and the benefit payments for the non-qualified (supplemental) pension and OPEB plans:      Pension  Millions Qualified Non-qualified OPEB  2017 $ - $ 24 $ 22  2016 100 24 23  Our policy with respect to funding the qualified plans is to fund at least the minimum required by law and not more than the maximum amount deductible for tax purposes. All contributions made to the qualified pension plans were voluntary and were made with cash generated from operations.  The non-qualified pension and OPEB plans are not funded and are not subject to any minimum regulatory funding requirements. Benefit payments for each year represent supplemental pension payments and claims paid for medical and life insurance. We anticipate our 2018 supplemental pension and OPEB payments will be made from cash generated from operations.  Benefit Payments  The following table details expected benefit payments for the years 2018 through 2027 :      Millions Pension OPEB  2018 $ 212 $ 23  2019 212 22  2020 211 22  2021 212 21  2022 213 20  Years 2023 - 2027 1,101 90  Asset Allocation Strategy  Our pension plan asset allocation at December 31, 2017, and 2016 , and target allocation for 2018 , are as follows:      Percentage of Plan Assets  Target December 31,  Allocation 2018 2017 2016  Equity securities 60% to 70% 69% 68%  Debt securities 20% to 30% 22 21  Real estate 2% to 8% 5 6  Commodities 4% to 6% 4 5  Total 100% 100%  The investment strategy for pension plan assets is to maintain a broadly diversified portfolio designed to achieve our target average long-term rate of return of 7.0% . While we believe we can achieve a long-term average rate of return of 7.0%, we cannot be certain that the portfolio will perform to our expectations. Assets are strategically allocated among equity, debt, and other investments in order to achieve a diversification level that reduces fluctuations in investment returns. Asset allocation target ranges for equity, debt, and other portfolios are evaluated at least every three years with the assistance of an independent consulting firm. Actual asset allocations are monitored monthly, and rebalancing actions are executed at least quarterly, as needed.  The pension plan investments are held in a Master Trust. The majority of pension plan assets are invested in equity securities because equity portfolios have historically provided higher returns than debt and other asset classes over extended time horizons and are expected to do so in the future. Correspondingly, equity investments also entail greater risks than other investments. Equity risks are balanced by investing a significant portion of the plans’ assets in high quality debt securities. The average credit rating of the debt portfolio exceeded A at both December 31, 2017 and December 31, 2016 . The debt portfolio is also broadly diversified and invested primarily in U.S. Treasury, mortgage, and corporate securities. The weighted-average maturity of the debt portfolio was 13 years and 14 years at December 31, 2017, and 2016, respectively.  The investment of pension plan assets in securities issued by UPC is explicitly prohibited by the plan for both the equity and debt portfolios, other than through index fund holdings.  Fair Value Measurements  The pension plan assets are valued at fair value. The following is a description of the valuation methodologies used for the investments measured at fair value, including the general classification of such instruments pursuant to the valuation hierarchy.  Temporary Cash Investments – These investments consist of U.S. dollars and foreign currencies held in master trust accounts at The Northern Trust Company (the Trustee). Foreign currencies held are reported in terms of U.S. dollars based on currency exchange rates readily available in active markets. These temporary cash investments are classified as Level 1 investments.  Registered Investment Companies – Registered Investment Companies are entities primarily engaged in the business of investing in securities and are registered with the Securities and Exchange Commission. The Plan’s holdings of Registered Investment Companies include both public and private fund vehicles. The public vehicles are mutual funds (real estate) and exchange-traded funds (stocks), which are classified as Level 1 investments. The private vehicles (bonds) do not have published pricing and are valued using Net Asset Value (NAV).  Federal Government Securities – Federal Government Securities consist of bills, notes, bonds, and other fixed income securities issued directly by the U.S. Treasury or by government-sponsored enterprises. These assets are valued using a bid evaluation process with bid data provided by independent pricing sources. Federal Government Securities are classified as Level 2 investments.  Bonds and Debentures – Bonds and de bentures consist of debt securities issued by U.S. and non-U.S. corporations as well as state and local governments. These assets are valued using a bid evaluation process with bid data provided by independent pricing sources. Corporate, state, and municipal bonds and debentures are classified as Level 2 investments.  Corporate Stock – This investment category consists of common and preferred stock issued by U.S. and non-U.S. corporations. Most common shares are traded actively on exchanges and price quotes for these shares are readily available. Common stock is classified as a Level 1 investment. Preferred shares included in this category are valued using a bid evaluation process with bid data provided by independent pricing sources. Preferred stock is classified as a Level 2 investment.  Venture Capital and Buyout Partnerships – This investment category is comprised of interests in limited partnerships that invest primarily in privately-held companies. Due to the private nature of the partnership investments, pricing inputs are not readily observable. Asset valuations are developed by the general partners that manage the partnerships. These valuations are based on the application of public market multiples to private company cash flows, market transactions that provide valuation information for comparable companies, and other methods. The fair value recorded by the Plan is calculated using each partnership’s NAV.  Real Estate Partnerships – Mo st of t he Plan’s real estate investments are primarily interests in private real estate investment trusts , partnerships, limited liability companies , and similar structures . Valuations for the holdings in this category are not based on readily observable inputs and are primarily derived from property appraisals. The fair value recorded by the Plan is calculated using the NAV for each investment.  Collective Trust and Other Fund s – Collective trust and other funds are comprised of shares or units in commingled funds and limited liability companies that are not publicly traded. The underlying assets in these entities (U.S. stock funds, non-U.S. stock funds, commodity funds, hedge funds, and short term investment funds) are publicly traded on exchanges and price quotes for the assets held by these funds are readily available. The fair value recorded by the Plan is calculated using NAV for each investment.  As of December 31, 2017 , the pension plan assets measured at fair value on a recurring basis were as follows:       Quoted Prices Significant  in Active Other Significant  Markets for Observable Unobservable  Identical Inputs Inputs Inputs  Millions (Level 1) (Level 2) (Level 3) Total  Plan assets at fair value:  Temporary cash investments $ 27 $ $ - $ 27  Registered investment companies [a] 4 - 4  Federal government securities 182 - 182  Bonds and debentures 389 - 389  Corporate stock 1,171 8 - 1,179  Total plan assets at fair value $ 1,202 $ 579 $ - $ 1,781  Plan assets at NAV:  Registered investment companies [b] 329  Venture capital and buyout partnerships 358  Real estate partnerships 226  Collective trust and other funds 1,552  Total plan assets at NAV $ 2,465  Other assets [c] (22)  Total plan assets $ 4,224  [a] Registered investment companies measured at fair val ue include stock investments. [b] Registered investment companies measured at NAV include bond investments. [c] Other assets include accrued receivables , net payables, and pending broker settlements.  As of December 31, 2016 , the pension plan assets measured at fair value on a recurring basis were as follows:      Quoted Prices Significant  in Active Other Significant  Markets for Observable Unobservable  Identical Inputs Inputs Inputs  Millions (Level 1) (Level 2) (Level 3) Total  Plan assets at fair value:  Temporary cash investments $ 27 $ - $ - $ 27  Registered investment companies [a] 17 - - 17  Federal government securities - 142 - 142  Bonds and debentures - 357 - 357  Corporate stock 1,059 8 - 1,067  Total plan assets at fair value $ 1,103 $ 507 $ - $ 1,610  Plan assets at NAV:  Registered investment companies [b] 280  Venture capital and buyout partnerships 283  Real estate partnerships 212  Collective trust and other funds 1,346  Total plan assets at NAV $ 2,121  Other assets [c] 17  Total plan assets $ 3,748  [a] Registered investment companies measured at fair value include stock and real estate investments. [b] Registered investment companies measured at NAV include bond investments. [c] Other assets include accrued receivables and pending broker settlements.  For the years ended December 31, 2017 and 2016 , there were no significant transfers in or out of Levels 1, 2, or 3.  The Master Trust’s investments in limited partnerships and similar structures (used to invest in private equity and real estate) are valued at fair value based on their proportionate share of the partnerships’ fair value as recorded in the limited partnerships’ audited financial statements. The limited partnerships allocate gains, losses and expenses to the partners based on the ownership percentage as described in the partnership agreements. At Dece mber 31, 2017 and 2016 , the Master Trust had future commitments for additional contributions to private equity pa rtnerships totaling $359 million and $392 million , respectively, and to real estate partnership s and funds totaling $67 million and $32 million, respectively.  Other Retirement Programs  401(k)/Thrift Plan – For non-union employees hired prior to January 1, 2018, and eligible union employees for whom we make matching contributions, we provide a defined contribution plan (401(k)/thrift plan). We match 50 cents for each dollar contributed by employees up to the first 6% of compensation contributed. Our plan contributions were $19 million in 2017, $19 m illion in 2016, and $20 million in 2015. For non-union employees hired on or after January 1, 2018 , we will match dollar -for-dollar, up to the first 6% of compensation contributed, in addition to contributing an annual amount of 3% of the employee’s annual base salary.  Railroad Retirement System – All Railroad employees are covered by the Railroad Retirement System (the System). Contributions made to the System are expensed as incurred and amounted to approximately $672 million in 2017, $671 m illion in 2016, and $749 million in 2015.  Collective Bargaining Agreements – Under collective bargaining agreements, we participate in multi-employer benefit plans that provide certain postretirement health care and life insurance benefits for eligible union employees. Premiums paid under these plans are expensed as incurred and amounted to $60 million in 2017, $50 million in 2016 , and $46 million in 2015. 

Other Income

Other Income	12 Months Ended
	Dec. 31, 2017
Other Income [Abstract]
Other Income	7. Other Income  Other income included the following for the years ended December 31:      Millions 2017 2016 2015  Rental income [a] $ 178 $ 96 $ 96  Net gain on non-operating asset dispositions [b] [c] 111 94 144  Interest income 16 11 5  Non-operating environmental costs and other (15) (9) (19)  Total $ 290 $ 192 $ 226  [a] 2017 includes $65 million related to a favorable litigation settlement . [b] 2017 includes $26 million and $57 million related to a real estate sale in the first quarter and in the third quarter , respectively . [c] 2016 includes $17 million and $50 million related to a real estate sale in the first quarter and second quarter , respectively .

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Income Taxes	8. Income Taxes  Components of income tax expense were as follows for the years ended December 31:      Millions 2017 2016 2015  Current tax expense:  Federal $ 1,750 $ 1,518 $ 1,901  State 235 176 210  Foreign 2 8 8  Total current tax expense 1,987 1,702 2,119  Deferred and other tax expense:  Federal (5,260) 692 644  State 183 139 121  Foreign 10 - -  Total deferred and other tax expense [a] (5,067) 831 765  Total income tax expense $ (3,080) $ 2,533 $ 2,884  [a] 2017 includes a $(5,935) million adjustment to income tax expense resulting from the Tax Cuts and Jobs Act. Of this amount, $(5,965) million is a federal income tax benefit and $30 million is a state income tax expense.  For the years ended December 31, reconciliations between statutory and effective tax rates are as follows:      Tax Rate Percentages 2017 2016 2015  Federal statutory tax rate 35.0 % 35.0 % 35.0 %  State statutory rates, net of federal benefits 3.1 3.1 3.1  Adjustment for Tax Cuts and Jobs Act (77.8) - -  Other deferred tax adjustments 0.4 - -  Tax credits 0.1 (0.5) (0.5)  Other (1.2) (0.2) 0.1  Effective tax rate (40.4) % 37.4 % 37.7 %  Deferred tax assets and liabilities are recorded for the expected future tax consequences of events that are reported in different periods for financial reporting and income tax purposes. The majority of our deferred tax assets relate to deductions that already have been claimed for financial reporting purposes but not for tax purposes. The majority of our deferred tax liabilities relate to differences between the tax bases and financial reporting amounts of our land and depreciable property, due to accelerated tax depreciation (including bonus depreciation), revaluation of assets in purchase accounting transactions, and differences in capitalization methods.  The Tax Cuts and Jobs Act (the “Tax Act”) was enacted on December 22, 2017. The Tax Act made significant changes to federal tax law, including a reduction in the federal income tax rate from 35% to 21% effective January 1, 2018, 100% bonus depreciation for certain capital expenditures, stricter limits on deductions for interest and certain executive compensation, and a one-time transition tax on previously deferred earnings of certain foreign subsidiaries. As a result of our initial analysis of the Tax Act and existing implementation guidance, we remeasured our deferred tax assets and liabilities and computed our transition tax liability net of offsetting foreign tax credits. This resulted in a $5.9 billion reduction in our income tax expense in 2017. We also recorded a $212 million reduction to our operating expense related to income tax adjustments at equity-method affiliates.  The SEC provided guidance in SAB 118 on accounting for the tax effects of the Tax Act (See Note 3). In accordance with that guidance, some of the income tax effects recorded in 2017 are provisional, including those related to our analysis of 100% bonus depreciation for certain capital expenditures, stricter limits on deductions for certain executive compensation, the one-time transition tax, and the reduction to our operating expense related to income tax adjustments at equity-method affiliates. The accounting for these income tax effects may be adjusted during 2018 as a result of continuing analysis of the Tax Act; additional implementation guidance from the IRS, state tax authorities, the SEC, the FASB, or the Joint Committee on Taxation; and new information from domestic or foreign equity affiliates.  On July 6, 2017, the State of Illinois increased its corporate income tax rate effective July 1, 2017. In the third quarter of 2017, we increased our deferred tax expense by $33 million to reflect the increased tax rate.  Deferred income tax (liabilities)/assets were comprised of the following at December 31:      Millions 2017[a] 2016  Deferred income tax liabilities:  Property $ (11,262) $ (16,687)  Other (197) (346)  Total deferred income tax liabilities (11,459) (17,033)  Deferred income tax assets:  Accrued wages 46 75  Accrued casualty costs 147 231  Stock compensation 46 69  Retiree benefits 141 222  Credits 1 145  Other 142 295  Total deferred income tax assets $ 523 $ 1,037  Net deferred income tax liability $ (10,936) $ (15,996)  [a] 2017 amounts reflect the provisional impact of the Tax Act.  When appropriate, we record a valuation allowance against deferred tax assets to reflect that these tax assets may not be realized. In determining whether a valuation allowance is appropriate, we consider whether it is more likely than not that all or some portion of our deferred tax assets will not be realized based on management’s judgments using available evidence for purposes of estimating whether future taxable income will be sufficient to realize a deferred tax asset. In 201 7 and 201 6 , there were no valuation allowances.  Tax benefits are recognized only for tax positions that are more likely than not to be sustained upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50 percent likely to be realized upon settlement. Unrecognized tax benefits are tax benefits claimed in our tax returns that do not meet these recognition and measurement standards.  A reconciliation of changes in unrecognized tax benefits liabilities/(assets) from the beginning to the end of the reporting period is as follows:      Millions 2017 2016 2015  Unrecognized tax benefits at January 1 $ 125 $ 94 $ 151  Increases for positions taken in current year 38 31 38  Increases for positions taken in prior years 51 10 13  Decreases for positions taken in prior years (56) (20) (87)  Refunds from/(payments to) and settlements with taxing authorities 64 4 (13)  Increases/(decreases) for interest and penalties - 6 (5)  Lapse of statutes of limitations (43) - (3)  Unrecognized tax benefits at December 31 $ 179 $ 125 $ 94  We recognize interest and penalties as part of income tax expense. Total accrued liabilities for interest and penalties were $ 8 million at both December 31, 2017, and 2016 . Total interest and penalties recognized as part of income tax expense (benefit) were $(3) million for 2017, $5 million for 2016, and $(3) million for 2015.  The statute of limitations has run for all years prior to 2014 and UPC is not currently under examination by the Internal Revenue Service (IRS) for any of its open years. In 2017, UPC amended its 2013 income tax returns, primarily to claim deductions resulting from the resolution of prior year IRS examinations . We have not received any communication from the IRS related to these amended returns.  In 2016, UPC amended its 2011 and 2012 income tax returns to claim deductions resulting from the resolution of IRS examinations for years prior to 2011. The IRS and Joint Committee on Taxation reviewed these amended returns. In the third quarter of 2017, we received a refund of $62 million, consisting of $60 million of tax and $2 million of interest.  In the third quarter of 2015, UPC and the IRS signed a closing agreement resolving all tax matters for tax years 2009-2010. The settlement had an immaterial effect on our income tax expense. In connection with the settlement, UPC paid $10 million in the fourth quarter of 2015.  Several state tax authorities are examining our state income tax returns for years 2010 through 2015.  We do not expect our unrecognized tax benefits to change significantly in the next 12 months.  The portion of our unrecognized tax benefits that relates to permanent changes in tax and interest would reduce our effective tax rate, if recognized. The remaining unrecognized tax benefits relate to tax positions for which only the timing of the benefit is uncertain. Recognition of the tax benefits with uncertain timing would reduce our effective tax rate only through a reduction of accrued interest and penalties. The unrecognized tax benefits that would reduce our effective tax rate are as follows:             Millions 2017 2016 2015  Unrecognized tax benefits that would reduce the effective tax rate $ 83 $ 31 $ 31  Unrecognized tax benefits that would not reduce the effective tax rate 96 94 63  Total unrecognized tax benefits $ 179 $ 125 $ 94 

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	 9. Earnings Per Share  The following table provides a reconciliation between basic and diluted earnings per share for the years ended December 31:      Millions, Except Per Share Amounts 2017 2016 2015  Net income $ 10,712 $ 4,233 $ 4,772  Weighted-average number of shares outstanding:  Basic 798.4 832.4 866.2  Dilutive effect of stock options 1.8 1.5 1.5  Dilutive effect of retention shares and units 1.5 1.5 1.7  Diluted 801.7 835.4 869.4  Earnings per share – basic $ 13.42 $ 5.09 $ 5.51  Earnings per share – diluted $ 13.36 $ 5.07 $ 5.49  Common stock options totaling 1.6 million, 2.0 million, and 1.1 million for 2017, 201 6 , and 201 5 , respectively, were excluded from the computation of diluted earnings per share because the exercise prices of these options exceeded the average market price of our common stock for the respective periods, and the effect of their inclusion would be anti-dilutive.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income/(Loss)	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Income/(Loss) [Abstract]
Accumulated Other Comprehensive Income/(Loss)	10. Accumulated Other Comprehensive Income/(Loss)  Reclassifications out of accumulated other comprehensive income/(loss) were as follows (net of tax):      Millions Defined benefit plans Foreign currency translation Total  Balance at January 1, 2017 $ (1,132) $ (140) $ (1,272)  Other comprehensive income/(loss) before reclassifications 2 28 30  Amounts reclassified from accumulated other comprehensive income/(loss) [a] 101 - 101  Net year-to-date other comprehensive income/(loss), net of taxes of $(61) million 103 28 131  Balance at December 31, 2017 $ (1,029) $ (112) $ (1,141)   Balance at January 1, 2016 $ (1,103) $ (92) $ (1,195)  Other comprehensive income/(loss) before reclassifications (3) (48) (51)  Amounts reclassified from accumulated other comprehensive income/(loss) [a] (26) - (26)  Net year-to-date other comprehensive income/(loss), net of taxes of $49 million (29) (48) (77)  Balance at December 31, 2016 $ (1,132) $ (140) $ (1,272)  [a] The accumulated other comprehensive income/(loss) reclassification components are 1) prior service cost/(benefit) and 2) net actuarial loss which are both included in the computation of net periodic pension cost. See Note 6 Retirement Plans for additional details.

Accounts Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2017
Accounts Receivable [Abstract]
Accounts Receivable	11. Accounts Receivable  Accounts receivable includes freight and other receivables reduced by an allowance for doubtful accounts. The allowance is based upon historical losses, credit worthiness of customers, and current economic conditions. At December 31, 2017, and 2016 , our accounts receivable were reduced by $3 million and $5 million , respectively . Receivables not expected to be collected in one year and the associated allowances are classified as other assets in our Consolidated Statements of Financial Position. At both December 31, 2017, and 2016 , receivables classified as other assets were reduced by allowances of $17 million .  Receivables Securitization Facility – The Railroad maintains a $650 million, 3 -year receivables securitization facility (the Receivables Facility), maturing in July 2019 . Under the Receivables Facility, the Railroad sells most of its eligible third-party receivables to Union Pacific Receivables, Inc. (UPRI), a consolidated, wholly-owned, bankruptcy-remote subsidiary that may subsequently transfer, without recourse, an undivided interest in accounts receivable to investors. The investors have no recourse to the Railroad’s other assets except for customary warranty and indemnity claims. Creditors of the Railroad do not have recourse to the assets of UPRI.  The amount outstanding under the Receivables F acility was $500 million and $0 at December 31, 2017 , and December 31, 2016 . The Receivables F acility was supported by $1.1 billion and $1.0 billion of accounts receivable as collateral at December 31, 2017 , and December 31, 2016 , respectively , which, as a retained interest, is included in accounts receivable, net in our Consolidated Statements of Financial Position.  The outstanding amount the Railroad is allowed to maintain under the Receivables F acility, with a maximum of $650 million, may fluctuate based on the availability of eligible receivables and is directly affected by business volumes and credit risks, including receivables payment quality measures such as default and dilution ratios. If default or dilution ratios increase one percent, the allowable outstanding amount under the Receivables F acility would not materially change.  The costs of the Receivables F acility include interest, which will vary based on prevailing benchmark and commercial paper rates, program fees paid to participating banks, commercial paper issuance costs, and fees of participating banks for unused commitment availability. The costs of the Receivables F acility are included in interest expense and were $6 million, $7 million , and $5 million for 2017, 201 6 , and 201 5 , respectively.

Properties

Properties	12 Months Ended
	Dec. 31, 2017
Properties [Abstract]
Properties	12. Properties  The following tables list the major categories of property and equipment, as well as the weighted-average estimated useful life for each category (in years):      Millions, Except Estimated Useful Life Accumulated Net Book Estimated  As of December 31, 2017 Cost Depreciation Value Useful Life  Land $ 5,258 $ N/A $ 5,258 N/A  Road:  Rail and other track material 16,327 5,929 10,398 43  Ties 10,132 2,881 7,251 33  Ballast 5,406 1,509 3,897 34  Other roadway [a] 18,972 3,482 15,490 47  Total road 50,837 13,801 37,036 N/A  Equipment:  Locomotives 9,686 3,697 5,989 19  Freight cars 2,255 983 1,272 24  Work equipment and other 936 267 669 19  Total equipment 12,877 4,947 7,930 N/A  Technology and other 1,105 460 645 11  Construction in progress 736 - 736 N/A  Total $ 70,813 $ 19,208 $ 51,605 N/A        Millions, Except Estimated Useful Life Accumulated Net Book Estimated  As of December 31, 2016 Cost Depreciation Value Useful Life  Land $ 5,220 $ N/A $ 5,220 N/A  Road:  Rail and other track material 15,845 5,722 10,123 40  Ties 9,812 2,736 7,076 33  Ballast 5,242 1,430 3,812 34  Other roadway [a] 18,138 3,226 14,912 47  Total road 49,037 13,114 35,923 N/A  Equipment:  Locomotives 9,692 3,939 5,753 20  Freight cars 2,243 972 1,271 24  Work equipment and other 905 232 673 19  Total equipment 12,840 5,143 7,697 N/A  Technology and other 974 412 562 11  Construction in progress 987 - 987 N/A  Total $ 69,058 $ 18,669 $ 50,389 N/A  [a] Other roadway includes grading, bridges and tunnels, signals, buildings, and other road assets.  Property and Depreciation – Our railroad operations are highly capital intensive, and our large base of homogeneous, network-type assets turns over on a continuous basis. Each year we develop a capital program for the replacement of assets and for the acquisition or construction of assets that enable us to enhance our operations or provide new service offerings to customers. Assets purchased or constructed throughout the year are capitalized if they meet applicable minimum units of property criteria. Properties and equipment are carried at cost and are depreciated on a straight-line basis over their estimated service lives, which are measured in years, except for rail in high-density traffic corridors (i.e., all rail lines except for those subject to abandonment, yard and switching tracks, and electronic yards) for which lives are measured in millions of gross tons per mile of track. We use the group method of depreciation in which all items with similar characteristics, use, and expected lives are grouped together in asset classes, and are depreciated using composite depreciation rates. The group method of depreciation treats each asset class as a pool of resources, not as singular items. We currently have more than 60 depreciable asset classes, and we may increase or decrease the number of asset classes due to changes in technology, asset strategies, or other factors.  We determine the estimated service lives of depreciable railroad assets by means of depreciation studies. We perform depreciation studies at least every three years for equipment and every six years for track assets (i.e., rail and other track material, ties, and ballast) and other road property. Our depreciation studies take into account the following factors:  · Statistical analysis of historical patterns of use and retirements of each of our asset classes; · Evaluation of any expected changes in current operations and the outlook for continued use of the assets; · Evaluation of technological advances and changes to maintenance practices; and · Expected salvage to be received upon retirement.  For rail in high-density traffic corridors, we measure estimated service lives in millions of gross tons per mile of track. It has been our experience that the lives of rail in high-density traffic corridors are closely correlated to usage (i.e., the amount of weight carried over the rail). The service lives also vary based on rail weight, rail condition (e.g., new or secondhand), and rail type (e.g., straight or curve). Our depreciation studies for rail in high-density traffic corridors consider each of these factors in determining the estimated service lives. For rail in high-density traffic corridors, we calculate depreciation rates annually by dividing the number of gross ton-miles carried over the rail (i.e., the weight of loaded and empty freight cars, locomotives and maintenance of way equipment transported over the rail) by the estimated service lives of the rail measured in millions of gross tons per mile. For all other depreciable assets, we compute depreciation based on the estimated service lives of our assets as determined from the analysis of our depreciation studies. Changes in the estimated service lives of our assets and their related depreciation rates are implemented prospectively.  Under group depreciation, the historical cost (net of salvage) of depreciable property that is retired or replaced in the ordinary course of business is charged to accumulated depreciation and no gain or loss is recognized. The historical cost of certain track assets is estimated by multiplying the current replacement cost of track assets by a historical index factor derived from (i) inflation indices published by the Bureau of Labor Statistics and (ii) the estimated useful lives of the assets as determined by our depreciation studies. The indices were selected because they closely correlate with the major costs of the properties comprising the applicable track asset classes. Because of the number of estimates inherent in the depreciation and retirement processes and because it is impossible to precisely estimate each of these variables until a group of property is completely retired, we continually monitor the estimated service lives of our assets and the accumulated depreciation associated with each asset class to ensure our depreciation rates are appropriate. In addition, we determine if the recorded amount of accumulated depreciation is deficient (or in excess) of the amount indicated by our depreciation studies. Any deficiency (or excess) is amortized as a component of depreciation expense over the remaining service lives of the applicable classes of assets.  For retirements of depreciable railroad properties that do not occur in the normal course of business, a gain or loss may be recognized if the retirement meets each of the following three conditions: (i) is unusual, (ii) is material in amount, and (iii) varies significantly from the retirement profile identified through our depreciation studies. A gain or loss is recognized in other income when we sell land or dispose of assets that are not part of our railroad operations.  When we purchase an asset, we capitalize all costs necessary to make the asset ready for its intended use. However, many of our assets are self-constructed. A large portion of our capital expenditures is for replacement of existing track assets and other road properties, which is typically performed by our employees, and for track line expansion and other capacity projects. Costs that are directly attributable to capital projects (including overhead costs) are capitalized. Direct costs that are capitalized as part of self-constructed assets include material, labor, and work equipment. Indirect costs are capitalized if they clearly relate to the construction of the asset.  Normal repairs and maintenance are expensed as incurred, while costs incurred that extend the useful life of an asset, improve the safety of our operations or improve operating efficiency are capitalized. These costs are allocated using appropriate statistical bases. Total expense for repairs and maintenance incurred was $2.5 billion for 2017, $2.3 billion for 2016, and $2.5 billion for 2015.  Assets held under capital leases are recorded at the lower of the net present value of the minimum lease payments or the fair value of the leased asset at the inception of the lease. Amortization expense is computed using the straight-line method over the shorter of the estimated useful lives of the assets or the period of the related lease.

Accounts Payable And Other Curr

Accounts Payable And Other Current Liabilities	12 Months Ended
	Dec. 31, 2017
Accounts Payable And Other Current Liabilties [Abstract]
Accounts Payable And Other Current Liabilities	13. Accounts Payable and Other Current Liabilities     Dec. 31, Dec. 31,  Millions 2017 2016  Accounts payable $ 1,013 $ 955  Income and other taxes payable 547 472  Accrued wages and vacation 384 387  Interest payable 220 212  Accrued casualty costs 194 185  Equipment rents payable 110 101  Other 671 570  Total accounts payable and other current liabilities $ 3,139 $ 2,882

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2017
Financial Instruments [Abstract]
Financial Instruments	14. Financial Instruments  Short-Term Investments – The Company’s short-term investments consist of time deposits and government agency securities. These investments are considered level 2 investments and are valued at amortized cost, which approximates fair value ( $90 million of time deposits as of December 31, 2017). All short-term investments have a maturity of less than one year and are classified as held-to-maturity. There were no transfers out of Level 2 during the year ended December 31, 201 7 .  Fair Value of Financial Instruments – The fair value of our short- and long-term debt was estimated using a market value price model, which utilizes applicable U.S. Treasury rates along with current market quotes on comparable debt securities. All of the inputs used to determine the fair market value of the Corporation’s long-term debt are Level 2 inputs and obtained from an independent source. At December 31, 2017 , the fair value of total debt was $18.2 billion, approximately $1.3 billion more than the carrying value. At December 31, 2016 , the fair value of total debt was $15.9 billion, approximately $0.9 billion more than the carrying value. The fair value of the Corporation’s debt is a measure of its current value under present market conditions. It does not impact the financial statements under current accounting rules. At both December 31, 2017, and 2016 , approximately $155 million of debt securities contained call provisions that allow us to retire the debt instruments prior to final maturity at par , with out the payment of fixed call premi ums . The fair value of our cash equivalents approximates their carrying value due to the short-term maturities of these instruments.

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt [Abstract]
Debt	15. Debt  Total debt as of December 31, 2017, and 2016 , is summarized below:      Millions 2017 2016  Notes and debentures, 1.8% to 7.9% due through 2067 $ 15,096 $ 13,547  Capitalized leases, 3.1% to 8.4% due through 2028 892 1,105  Equipment obligations, 2.6% to 6.7% due through 2031 1,018 1,069  Term loans - floating rate, due in 2018 250 100  Mortgage bonds, 4.8% due through 2030 57 57  Medium-term notes, 9.3% to 10.0% due through 2020 18 23  Receivables Securitization (Note 11) 500 -  Unamortized discount and deferred issuance costs (887) (894)  Total debt 16,944 15,007  Less: current portion (800) (758)  Total long-term debt $ 16,144 $ 14,249  Debt Maturities – The following table presents aggregate debt maturities as of December 31, 2017 , excluding market value adjustments:      Millions  2018 $ 806  2019 1,125  2020 1,021  2021 677  2022 917  Thereafter 13,285  Total principal 17,831  Unamortized discount and deferred issuance costs (887)  Total debt $ 16,944  Equipment Encumbrances – Equipment with a carrying value of approximately $2.0 billion and $2.3 billion at December 31, 2017, and 2016 , respectively, served as collateral for capital leases and other types of equipment obligations in accordance with the secured financing arrangements utilized to acquire or refinance such railroad equipment.  As a result of the merger of Missouri Pacific Railroad Company (MPRR) with and into UPRR on January 1, 1997, and pursuant to the underlying indentures for the MPRR mortgage bonds, UPRR must maintain the same value of assets after the merger in order to comply with the security requirements of the mortgage bonds. As of the merger date, the value of the MPRR assets that secured the mortgage bonds was approximately $6.0 billion. In accordance with the terms of the indentures, this collateral value must be maintained during the entire term of the mortgage bonds irrespective of the outstanding balance of such bonds.  Credit Facilities – At December 31, 2017 , we had $1.7 billion of credit available under our revolving credit facility, which is designated for general corporate purposes and supports the issuance of commercial paper. We did not draw on the facility during 2017. Commitment fees and interest rates payable under the facility are similar to fees and rates available to comparably rated, investment-grade borrowers. The facility allows for borrowings at floating rates based on London Interbank Offered Rates, plus a spread, depending upon credit ratings for our senior unsecured debt. The facility matures in May 2019 under a five -year term and requires UPC to maintain a debt-to-net-worth coverage ratio.  The definition of debt used for purposes of calculating the debt-to-net-worth coverage ratio includes, among other things, certain credit arrangements, capital leases, guarantees and unfunded and vested pension benefits under Title IV of ERISA. At December 31, 2017 , the debt-to-net-worth coverage ratio allowed us to carry up to $49.7 billion of debt (as defined in the facility), and we had $17.0 billion of debt (as defined in the facility) outstanding at that date. Under our current financial plans, we expect to continue to satisfy the debt-to-net-worth coverage ratio; however, many factors beyond our reasonable control could affect our ability to comply with this provision in the future. The facility does not include any other financial restrictions, credit rating triggers (other than rating-dependent pricing), or any other provision that could require us to post collateral. The facility also includes a $125 million cross-default provision and a change-of-control provision.  During 2017, we did not issue or repay any commercial paper, and at December 31, 2017, and 2016 , we had no commercial paper outstanding . Our revolving credit facility supports our outstanding commercial paper balances, and, unless we change the terms of our commercial paper program, our aggregate issuance of commercial paper will not exceed the amount of borrowings available under the facility.  Dividend Restrictions – Our revolving credit facility includes a debt-to-net worth covenant (discussed in the Credit Facilities section above) that, under certain circumstances, restricts the payment of cash dividends to our shareholders. The amount of retained earnings available for dividends was $16.4 billion and $12.4 billion at December 31, 2017, and 2016 , respectively .  Shelf Registration Statement and Significant New Borrowings – In 2016, the Board of Directors reauthorized the issuance of up to $4.0 billion of debt securities. Under our shelf registration, we may issue, from time to time, any combination of debt securities, preferred stock, common stock, or warrants for debt securities or preferred stock in one or more offerings.  During 2017 , we issued the following unsecured, fixed-rate debt securities under our current shelf registration:       Date Description of Securities  April 5, 2017 $500 million of 3.000% Notes due April 15, 2027  $500 million of 4.000% Notes due April 15, 2047  September 19, 2017 $500 million of 3.600% Notes due September 15, 2037  $500 million of 4.100% Notes due September 15, 2067  We used the net proceeds from the offerings for general corporate purposes, including the repurchase of common stock pursuant to our share repurchase program. These debt securities include change-of-control provisions . At December 31, 2017 , we had remaining authority to issue up to $1.55 billion of debt securities under our shelf registration.  Receivables Securitization Facility – As of December 31, 2017, and 2016 , we recorded $500 million and $0 , respect ively, of borrowings under our R e ceivables F acility, as secured debt. (See further discussion of our receivables securitization facility in Note 11).

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2017
Variable Interest Entities [Abstract]
Variable Interest Entities	16. Variable Interest Entities  We have entered into various lease transactions in which the structure of the leases contain variable interest entities (VIEs). These VIEs were created solely for the purpose of doing lease transactions (principally involving railroad equipment and facilities) and have no other activities, assets or liabilities outside of the lease transactions. Within these lease arrangements, we have the right to purchase some or all of the assets at fixed prices. Depending on market conditions, fixed-price purchase options available in the leases could potentially provide benefits to us; however, these benefits are not expected to be significant.  We maintain and operate the assets based on contractual obligations within the lease arrangements, which set specific guidelines consistent within the railroad industry. As such, we have no control over activities that could materially impact the fair value of the leased assets. We do not hold the power to direct the activities of the VIEs and, therefore, do not control the ongoing activities that have a significant impact on the economic performance of the VIEs. Additionally, we do not have the obligation to absorb losses of the VIEs or the right to receive benefits of the VIEs that could potentially be significant to the VIEs.  We are not considered to be the primary beneficiary and do not consolidate these VIEs because our actions and decisions do not have the most significant effect on the VIE’s performance and our fixed-price purchase options are not considered to be potentially significant to the VIEs. The future minimum lease payments associated with the VIE leases totaled $1.9 billion as of December 31, 2017 .

Leases

Leases	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Leases	17. Leases  We lease certain locomotives, freight cars, and other property. The Consolidated Statements of Financial Position as of December 31, 2017, and 2016 included $1,635 million, net of $953 million of accumulated depreciation, and $1,997 million, net of $1,121 million of accumulated depreciation, respectively, for properties held under capital leases. A charge to income resulting from the depreciation for assets held under capital leases is included within depreciation expense in our Consolidated Statements of Income. Future minimum lease payments for operating and capital leases with initial or remaining non-cancelable lease terms in excess of one year as of December 31, 2017 , were as follows:      Millions Operating Leases Capital Leases  2018 $ 398 $ 173  2019 359 156  2020 297 164  2021 259 168  2022 221 147  Later years 1,115 271  Total minimum lease payments $ 2,649 $ 1,079  Amount representing interest N/A (187)  Present value of minimum lease payments N/A $ 892  Approximately 97% of capital lease payments relate to locomotives. Rent expense for operating leases with terms exceeding one month was $480 million in 2017, $535 million in 201 6 , and $590 million in 201 5 . When cash rental payments are not made on a straight-line basis, we recognize variable rental expense on a straight-line basis over the lease term. Contingent rentals and sub-rentals are not significant.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies [Abstract]
Commitments And Contingencies	18. Commitments and Contingencies  Asserted and Unasserted Claims – Various claims and lawsuits are pending against us and certain of our subsidiaries. We cannot fully determine the effect of all asserted and unasserted claims on our consolidated results of operations, financial condition, or liquidity. To the extent possible, we have recorded a liability where asserted and unasserted claims are considered probable and where such claims can be reasonably estimated. We do not expect that any known lawsuits, claims, environmental costs, commitments, contingent liabilities, or guarantees will have a material adverse effect on our consolidated results of operations, financial condition, or liquidity after taking into account liabilities and insurance recoveries previously recorded for these matters.  Personal Injury – The cost of personal injuries to employees and others related to our activities is charged to expense based on estimates of the ultimate cost and number of incidents each year. We use an actuarial analysis to measure the expense and liability, including unasserted claims. The Federal Employers’ Liability Act (FELA) governs compensation for work-related accidents. Under FELA, damages are assessed based on a finding of fault through litigation or out-of-court settlements. We offer a comprehensive variety of services and rehabilitation programs for employees who are injured at work.  Our personal injury liability is not discounted to present value due to the uncertainty surrounding the timing of future payments. Approximately 95% of the recorded liability is related to asserted claims and approximately 5% is related to unasserted claims at December 31, 2017 . Because of the uncertainty surrounding the ultimate outcome of personal injury claims, it is reasonably possible that future costs to settle these claims may range from approximately $285 million to $310 million. We record an accrual at the low end of the range as no amount of loss within the range is more probable than any other. Estimates can vary over time due to evolving trends in litigation.  Our personal injury liability activity was as follows:      Millions 2017 2016 2015  Beginning balance $ 290 $ 318 $ 335  Current year accruals 77 75 89  Changes in estimates for prior years (7) (29) (3)  Payments (75) (74) (103)  Ending balance at December 31 $ 285 $ 290 $ 318  Current portion, ending balance at December 31 $ 66 $ 62 $ 63  In conjunction with the liability update performed in 2017, we also reassessed our estimated insurance recoveries. We have recognized an asset for estimated insurance recoveries at December 31, 2017, and 2016 . Any changes to recorded insurance recoveries are included in the above table in the Changes in estimates for prior years category.  Asbestos – We are a defendant in a number of lawsuits in which current and former employees and other parties allege exposure to asbestos. We assess our potential liability using a statistical analysis of resolution costs for asbestos-related claims. This liability is updated annually and excludes future defense and processing costs. The liability for resolving both asserted and unasserted claims was based on the following assumptions:  · The ratio of future claims by alleged disease would be consistent with historical averages adjusted for inflation. · The number of claims filed against us will decline each year. · The average settlement values for asserted and unasserted claims will be equivalent to historical averages. · The percentage of claims dismissed in the future will be equivalent to historical averages.  Our liability for asbestos-related claims is not discounted to present value due to the uncertainty surrounding the timing of future payments. Approximately 16% of the recorded liability related to asserted claims and approximately 84% related to unasserted claims at December 31, 2017 . Because of the uncertainty surrounding the ultimate outcome of asbestos -related claims, it is reasonably possible that future costs to settle these claims may range from approximately $99 million to $105 million. We record an accrual at the low end of the range as no amount of loss within the range is more probable than any other.  Our asbestos-related liability activity was as follows:      Millions 2017 2016 2015  Beginning balance $ 111 $ 120 $ 126  Accruals/(Credits) (1) 12 -  Payments (11) (21) (6)  Ending balance at December 31 $ 99 $ 111 $ 120  Current portion, ending balance at December 31 $ 9 $ 8 $ 6  In conjunction with the liability update performed in 2017, we also reassessed our estimated insurance recoveries. We have recognized an asset for estimated insurance recoveries at December 31, 2017, and 2016 . The amounts recorded for asbestos-related liabilities and related insurance recoveries were based on currently known facts. However, future events, such as the number of new claims filed each year, average settlement costs, and insurance coverage issues, could cause the actual costs and insurance recoveries to be higher or lower than the projected amounts. Estimates also may vary in the future if strategies, activities, and outcomes of asbestos litigation materially change; federal and state laws governing asbestos litigation increase or decrease the probability or amount of compensation of claimants; and there are material changes with respect to payments made to claimants by other defendants.  Environmental Costs – We are subject to federal, state, and local environmental laws and regulations. We have identified 315 sites at which we are or may be liable for remediation costs associated with alleged contamination or for violations of environmental requirements. This includes 33 sites that are the subject of actions taken by the U.S. government, 21 of which are currently on the Superfund National Priorities List. Certain federal legislation imposes joint and several liability for the remediation of identified sites; consequently, our ultimate environmental liability may include costs relating to activities of other parties, in addition to costs relating to our own activities at each site.  When we identify an environmental issue with respect to property owned, leased, or otherwise used in our business, we perform, with assistance of our consultants, environmental assessments on the property. We expense the cost of the assessments as incurred. We accrue the cost of remediation where our obligation is probable and such costs can be reasonably estimated. Our environmental liability is not discounted to present value due to the uncertainty surrounding the timing of future payments.  Our environmental liability activity was as follows:      Millions 2017 2016 2015  Beginning balance $ 212 $ 190 $ 182  Accruals 45 84 61  Payments (61) (62) (53)  Ending balance at December 31 $ 196 $ 212 $ 190  Current portion, ending balance at December 31 $ 57 $ 55 $ 52  The environmental liability includes future costs for remediation and restoration of sites, as well as ongoing monitoring costs, but excludes any anticipated recoveries from third parties. Cost estimates are based on information available for each site, financial viability of other potentially responsible parties, and existing technology, laws, and regulations. The ultimate liability for remediation is difficult to determine because of the number of potentially responsible parties, site-specific cost sharing arrangements with other potentially responsible parties, the degree of contamination by various wastes, the scarcity and quality of volumetric data related to many of the sites, and the speculative nature of remediation costs. Estimates of liability may vary over time due to changes in federal, state, and local laws governing environmental remediation. Current obligations are not expected to have a material adverse effect on our consolidated results of operations, financial condition, or liquidity.  Insurance – The Company has a consolidated, wholly-owned captive insurance subsidiary (the captive), that provides insurance coverage for certain risks including FELA claims and property coverage which are subject to reinsurance. The captive entered into annual reinsurance treaty agreements that insure workers compensation, general liability, auto liability and FELA risk. The captive cedes a portion of its FELA exposure through the treaty and assumes a proportionate share of the entire risk. The captive receives direct premiums, which are netted against the Company’s premium costs in other expenses in the Consolidated Statements of Income. The treaty agreements provide for certain protections against the risk of treaty participants’ non-performance, and we do not believe our exposure to treaty participants’ non-performance is material at this time. In the event the Company leaves the reinsurance program, the Company is not relieved of its primary obligation to the policyholders for activity prior to the termination of the treaty agreements. We record both liabilities and reinsurance receivables using an actuarial analysis based on historical experience in our Consolidated Statements of Financial Position.  Guarantees – At December 31, 2017, and 2016 , we were contingently liable for $33 million and $43 million in guarantees, respectively. The fair value of these obligations as of both December 31, 2017, and 2016 was $0 . We entered into these contingent guarantees in the normal course of business, and they include guaranteed obligations related to our affiliated operations . The final guarantee expires in 2022. We are not aware of any existing event of default that would require us to satisfy these guarantees . We do not expect that these guarantees will have a material adverse effect on our consolidated financial condition, results of operations, or liquidity.  Indemnities – We are contingently obligated under a variety of indemnification arrangements, although in some cases the extent of our potential liability is limited, depending on the nature of the transactions and the agreements. Due to uncertainty as to whether claims will be made or how they will be resolved, we cannot reasonably determine the probability of an adverse claim or reasonably estimate any adverse liability or the total maximum exposure under these indemnification arrangements. We do not have any reason to believe that we will be required to make any material payments under these indemnity provisions. 

Share Repurchase Program

Share Repurchase Program	12 Months Ended
	Dec. 31, 2017
Share Repurchase Program [Abstract]
Share Repurchase Program	19. Share Repurchase Program  Effective January 1, 2017, our Board of Directors authorized the repurchase of up to 120 million shares of our common stock by December 31, 2020 , replacing our previous repurchase program. As of December 31, 2017 , we repurchased a total of $23.2 billion of our common stock since the commencement of our repurchase programs in 2007. The table below represents shares repurchased in 2017 under this repurchase program and shares repurchased in 2016 under our previous repurchase program.      Number of Shares Purchased Average Price Paid  2017 2016 2017 2016  First quarter 7,531,300 9,315,807 $ 106.55 $ 76.49  Second quarter 7,788,283 7,026,100 109.10 85.66  Third quarter 11,801,755 9,088,613 106.69 93.63  Fourth quarter 9,231,510 9,624,667 119.37 97.60  Total 36,352,848 35,055,187 $ 110.40 $ 88.57  Management's assessments of market conditions and other pertinent factors guide the timing and volume of all repurchases. Repurchased shares are recorded in treasury stock at cost, which includes any applicable commissions and fees.  From January 1, 2018, through February 8, 2018, we repurchased 2.6 million shares at an aggregate cost of approximately $349 million.

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2017
Related Parties [Abstract]
Related Parties	20. Related Parties  UPRR and other North American railroad companies jointly own TTX Company (TTX). UPRR has a 36.79% economic and voting interest in TTX while the other North American railroads own the remaining interest. In accordance with ASC 323 Investments - Equity Method and Joint Venture , UPRR applies the equity method of accounting to our investment in TTX.  TTX is a railcar pooling company that owns railcars and intermodal wells to serve North America’s railroads . TTX assists railroads in meet ing the needs of their customers by providing railcars in an efficient, pooled environment. All railroads have the ability to utilize TTX railcars through car hire by renting railcars at stated rates.  UPRR had $1. 2 billion and $877 million recognized as inv estments related to TTX in our Consolidated Statements of Financial Position as of December 31, 2017, and 2016 , respectively. TTX car hire expenses of $388 million in 2017, $368 million in 2016, and $376 million in 2015 are included in equipment and other rents in our Consolidated Statements of Income. In addition, UPRR had accounts payable to TTX of $69 million and $61 million at December 31, 2017, and 2016 , re spectively.

Selected Quarterly Data (Unaudi

Selected Quarterly Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Data (Unaudited) [Abstract]
Selected Quarterly Data (Unaudited)	21. Selected Quarterly Data (Unaudited)      Millions, Except Per Share Amounts  2017 Mar. 31 Jun. 30 Sep. 30 Dec. 31  Operating revenues $ 5,132 $ 5,250 $ 5,408 $ 5,450  Operating income 1,793 2,005 2,012 2,251  Net income 1,072 1,168 1,194 7,278  Net income per share:  Basic 1.32 1.45 1.50 9.29  Diluted 1.32 1.45 1.50 9.25      Millions, Except Per Share Amounts  2016 Mar. 31 Jun. 30 Sep. 30 Dec. 31  Operating revenues $ 4,829 $ 4,770 $ 5,174 $ 5,168  Operating income 1,687 1,660 1,960 1,965  Net income 979 979 1,131 1,144  Net income per share:  Basic 1.16 1.17 1.36 1.40  Diluted 1.16 1.17 1.36 1.39  Per share net income for the four quarters combined may not equal the per share net income for the year due to rounding.

Schedule Of Valuation And Quali

Schedule Of Valuation And Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Schedule Of Valuation And Qualifying Accounts [Abstract]
Schedule Of Valuation And Qualifying Accounts	SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS Union Pacific Corporation and Subsidiary Companies      Millions, for the Years Ended December 31, 2017 2016 2015  Allowance for doubtful accounts:  Balance, beginning of period $ 22 $ 16 $ 21  Charges/(reduction) to expense 1 23 1  Net recoveries/(write-offs) (3) (17) (6)  Balance, end of period $ 20 $ 22 $ 16  Allowance for doubtful accounts are presented in the Consolidated Statements of Financial Position as follows:  Current $ 3 $ 5 $ 5  Long-term 17 17 11  Balance, end of period $ 20 $ 22 $ 16  Accrued casualty costs:  Balance, beginning of period $ 716 $ 736 $ 757  Charges to expense 167 202 227  Cash payments and other reductions (199) (222) (248)  Balance, end of period $ 684 $ 716 $ 736  Accrued casualty costs are presented in the Consolidated Statements of Financial Position as follows:  Current $ 194 $ 185 $ 181  Long-term 490 531 555  Balance, end of period $ 684 $ 716 $ 736 

Significant Accounting Polici32

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Significant Accounting Policies [Abstract]
Principles Of Consolidation	Principles of Consolidation – The Consolidated Financial Statements include the accounts of Union Pacific Corporation and all of its subsidiaries. Investments in affiliated companies (20% to 50% owned) are accounted for using the equity method of accounting. All intercompany transactions are eliminated. We currently have no less than majority-owned investments that require consolidation under variable interest entity requirements. 
Cash And Cash Equivalents	Cash and Cash Equivalents – Cash equivalents consist of investments with original maturities of three months or less.
Accounts Receivables	Accounts Receivable – Accounts receivable includes receivables reduced by an allowance for doubtful accounts. The allowance is based upon historical losses, credit worthiness of customers, and current economic conditions. Receivables not expected to be collected in one year and the associated allowances are classified as other assets in our Consolidated Statements of Financial Position.
Investments	Investments – Investments represent our investments in affiliated companies (20% to 50% owned) that are accounted for under the equity method of accounting and investments in companies (less than 20% owned) accounted for under the cost method of accounting. The results of operations for our equity method investments that are integral to our operations are recorded in operating expenses. 
Materials and Supplies	Materials and Supplies – Materials and supplies are carried at the lower of average cost or market.
Property and Depreciation	Property and Depreciation – Properties and equipment are carried at cost and are depreciated on a straight-line basis over their estimated service lives, which are measured in years, except for rail in high-density traffic corridors (i.e., all rail lines except for those subject to abandonment, yard and switching tracks, and electronic yards), for which lives are measured in millions of gross tons per mile of track. We use the group method of depreciation in which all items with similar characteristics, use, and expected lives are grouped together in asset classes, and are depreciated using composite depreciation rates. The group method of depreciation treats each asset class as a pool of resources, not as singular items. We determine the estimated service lives of depreciable railroad assets by means of depreciation studies. Under the group method of depreciation, no gain or loss is recognized when depreciable property is retired or replaced in the ordinary course of business. 
Impairment of Long-lived Assets	Impairment of Long-lived Assets – We review long-lived assets, including identifiable intangibles, for impairment when events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If impairment indicators are present and the estimated future undiscounted cash flows are less than the carrying value of the long-lived assets, the carrying value is reduced to the estimated fair value as measured by the discounted cash flows. 
Revenue Recognition	Revenue Recognition – We recognize freight revenues as freight moves from origin to destination. The allocation of revenue between reporting periods is based on the relative transit time in each reporting period with expenses recognized as incurred. Other revenues, which include revenues earned by our subsidiaries, revenues from our commuter rail operations, and accessorial revenue, are recognized as service is performed or contractual obligations are met. Customer incentives, which are primarily provided for shipping a specified cumulative volume or shipping to/from specific locations, are recorded as a reduction to operating revenues based on actual or projected future customer shipments.
Translation of Foreign Currency	Translation of Foreign Currency – Our portion of the assets and liabilities related to foreign investments are translated into U.S. dollars at the exchange rates in effect at the balance sheet date. Revenue and expenses are translated at the average rates of exchange prevailing during the year. Unrealized gains or losses are reflected within common shareholders’ equity as accumulated other comprehensive income or loss.
Fair Value Measurements	Fair Value Measurements – We use a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The level in the fair value hierarchy within which the fair value measurement in its entirety falls is determined based on the lowest level input that is significant to the fair value measurement in its entirety. These levels include:  Level 1: Quoted market prices in active markets for identical assets or liabilities. Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data. Level 3: Unobservable inputs that are not corroborated by market data.  We have applied fair value measurements to our short term investments, pension plan assets and short- and long-term debt.
Stock-Based Compensation	Stock-Based Compensation – We have several stock-based compensation plans under which employees and non-employee directors receive stock options, nonvested retention shares, and nonvested stock units. We refer to the nonvested shares and stock units collectively as “retention awards”. We have elected to issue treasury shares to cover option exercises and stock unit vestings, while new shares are issued when retention shares are granted.  We measure and recognize compensation expense for all stock-based awards made to employees and directors, including stock options. Compensation expense is based on the calculated fair value of the awards as measured at the grant date and is expensed ratably over the service period of the awards (generally the vesting period). The fair value of retention awards is the closing stock price on the date of grant, while the fair value of stock options is determined by using the Black-Scholes option pricing model. 
Earnings Per Share	 Earnings Per Share – Basic earnings per share are calculated on the weighted-average number of common shares outstanding during each period. Diluted earnings per share include shares issuable upon exercise of outstanding stock options and stock-based awards where the conversion of such instruments would be dilutive.
Income Taxes	Income Taxes – We account for income taxes by recording taxes payable or refundable for the current year and deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in our financial statements or tax returns. These expected future tax consequences are measured based on current tax law; the effects of future tax legislation are not anticipated. Future tax legislation, such as a change in the corporate tax rate, could have a material impact on our financial condition, results of operations, or liquidity.  When appropriate, we record a valuation allowance against deferred tax assets to reflect that these tax assets may not be realized. In determining whether a valuation allowance is appropriate, we consider whether it is more likely than not that all or some portion of our deferred tax assets will not be realized, based on management’s judgments using available evidence for purposes of estimating whether future taxable income will be sufficient to realize a deferred tax asset.  We recognize tax benefits that are more likely than not to be sustained upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50 percent likely to be realized upon settlement. A liability for “unrecognized tax benefits” is recorded for any tax benefits claimed in our tax returns that do not meet these recognition and measurement standards. 
Pension And Postretirement Benefits	Pension and Postretirement Benefits – We incur certain employment-related expenses associated with pensions and postretirement health benefits. In order to measure the expense associated with these benefits, we must make various assumptions including discount rates used to value certain liabilities, expected return on plan assets used to fund these expenses, compensation increases, employee turnover rates, anticipated mortality rates, and expected future health care costs. The assumptions used by us are based on our historical experience as well as current facts and circumstances. We use an actuarial analysis to measure the expense and liability associated with these benefits.
Personal Injury	Personal Injury – The cost of injuries to employees and others on our property is charged to expense based on estimates of the ultimate cost and number of incidents each year. We use an actuarial analysis to measure the expense and liability. Our personal injury liability is not discounted to present value. Legal fees and incidental costs are expensed as incurred.
Asbestos	Asbestos – We estimate a liability for asserted and unasserted asbestos-related claims based on an assessment of the number and value of those claims. We use a statistical analysis to assist us in properly measuring our potential liability. Our liability for asbestos-related claims is not discounted to present value due to the uncertainty surrounding the timing of future payments. Legal fees and incidental costs are expensed as incurred.
Environmental	Environmental – When environmental issues have been identified with respect to property currently or formerly owned, leased, or otherwise used in the conduct of our business, we perform, with the assistance of our consultants, environmental assessments on such property. We expense the cost of the assessments as incurred. We accrue the cost of remediation where our obligation is probable and such costs can be reasonably estimated. We do not discount our environmental liabilities when the timing of the anticipated cash payments is not fixed or readily determinable. Legal fees and incidental costs are expensed as incurred.
Use Of Estimates	Use of Estimates – The preparation of our Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect certain reported assets and liabilities, and the disclosure of certain contingent assets and liabilities as of the date of the consolidated financial statements, as well as the reported amounts of revenue and expenses during the reporting period . Actual future results may differ from such estimates.

Nature Of Operations (Tables)

Nature Of Operations (Tables)	12 Months Ended
	Dec. 31, 2017
Nature Of Operations [Abstract]
Freight Revenue By Commodity Group	The following table provides freight revenue by commodity group:      Millions 2017 2016 2015  Agricultural Products $ 3,685 $ 3,625 $ 3,581  Automotive 1,998 2,000 2,154  Chemicals 3,596 3,474 3,543  Coal 2,645 2,440 3,237  Industrial Products 4,078 3,348 3,808  Intermodal 3,835 3,714 4,074  Total freight revenues $ 19,837 $ 18,601 $ 20,397  Other revenues 1,403 1,340 1,416  Total operating revenues $ 21,240 $ 19,941 $ 21,813 

Accounting Pronouncements (Tabl

Accounting Pronouncements (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Pronouncements [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	The retrospective impact of future adoption is shown in the table below:     Millions 2017 2016 2015  Increase/(decrease) in operating income $ 45 $ (29) $ 30  Increase/(decrease) in other income (45) 29 (30) 

Workforce Reduction Plan (Table

Workforce Reduction Plan (Tables)	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Workforce Reduction Plan [Table Text Block]	   Millions Compensation and  for the Year Ended December 31, 2017 Benefits Expense  Pension $ 69  Severance 12  Equity Compensation 5  Total $ 86 

Stock Options And Other Stock36

Stock Options And Other Stock Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Stock Options And Other Stock Plans [Abstract]
Schedule Of Stock-Based Compensation	Information regarding stock-based compensation appears in the table below:      Millions 2017 2016 2015  Stock-based compensation, before tax:  Stock options $ 19 $ 16 $ 17  Retention awards 84 66 81  Total stock-based compensation, before tax $ 103 $ 82 $ 98  Excess tax benefits from equity compensation plans $ 44 $ 28 $ 62 
Schedule Of Stock Options Weighted Average Assumptions	The table below shows the annual weighted-average assumptions used for valuation purposes:      Weighted-Average Assumptions 2017 2016 2015  Risk-free interest rate 2.0% 1.3% 1.3%  Dividend yield 2.3% 2.9% 1.8%  Expected life (years) 5.3 5.1 5.1  Volatility 21.7% 23.2% 23.4%  Weighted-average grant-date fair value of options granted $ 18.19 $ 11.36 $ 22.30 
Summary Of Stock Options Activity	A summary of s tock option activity during 2017 is presented below:      Options (thous.) Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (millions)  Outstanding at January 1, 2017 6,162 $ 73.13 5.9 yrs. $ 205  Granted 1,086 107.30 N/A N/A  Exercised (1,448) 56.69 N/A N/A  Forfeited or expired (170) 92.18 N/A N/A  Outstanding at December 31, 2017 5,630 $ 83.37 5.8 yrs. $ 286  Vested or expected to vest at December 31, 2017 5,607 $ 83.25 5.8 yrs. $ 285  Options exercisable at December 31, 2017 3,466 $ 75.96 4.2 yrs. $ 201 
Schedule Of Stock Option Exercises	Additional information regarding stock option exer cises appears in the following table :      Millions 2017 2016 2015  Intrinsic value of stock options exercised $ 88 $ 52 $ 50  Cash received from option exercises 59 39 27  Treasury shares repurchased for employee payroll taxes (18) (15) (12)  Tax benefit realized from option exercises 34 20 19  Aggregate grant-date fair value of stock options vested 20 19 19 
Schedule Of Retention Awards	Changes in our retention awards during 201 7 were as follows:      Shares (thous.) Weighted-Average Grant-Date Fair Value  Nonvested at January 1, 2017 2,789 $ 84.68  Granted 575 107.51  Vested (894) 70.91  Forfeited (157) 94.01  Nonvested at December 31, 2017 2,313 $ 95.04 
Schedule Of Performance Retention Awards, Present Value Calculation Assumptions	The assumptions used to calculate the present value of estimated future divide nds related to the February 2017 grant were as follows:      2017  Dividend per share per quarter $ 0.605  Risk-free interest rate at date of grant 1.5% 
Schedule Of Performance Retention Awards	Changes in our performa nce retention awards during 2017 were as follows:      Shares (thous.) Weighted-Average Grant-Date Fair Value  Nonvested at January 1, 2017 1,145 $ 86.23  Granted 461 101.38  Vested (255) 83.06  Unearned (110) 83.06  Forfeited (103) 91.36  Nonvested at December 31, 2017 1,138 $ 92.92 

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Plans [Abstract]
Schedule Of Changes In Projected Benefit Obligation And Plan Assets	Changes in our PBO and plan assets were as follows for the years ended December 31:      Funded Status Pension OPEB  Millions 2017 2016 2017 2016  Projected Benefit Obligation  Projected benefit obligation at beginning of year $ 4,110 $ 3,958 $ 334 $ 329  Service cost 90 84 2 1  Interest cost 142 143 10 11  Plan curtailment cost 20 - (1) -  Special termination cost 49 - - -  Actuarial loss 382 124 7 16  Gross benefits paid (264) (199) (22) (23)  Projected benefit obligation at end of year $ 4,529 $ 4,110 $ 330 $ 334  Plan Assets  Fair value of plan assets at beginning of year $ 3,748 $ 3,544 $ - $ -  Actual return on plan assets 716 279 - -  Voluntary funded pension plan contributions - 100 - -  Non-qualified plan benefit contributions 24 24 22 23  Gross benefits paid (264) (199) (22) (23)  Fair value of plan assets at end of year $ 4,224 $ 3,748 $ - $ -  Funded status at end of year $ (305) $ (362) $ (330) $ (334) 
Schedule Of Amounts Recognized In Statement Of Financial Position	Amounts recognized in the statement of financial position as of December 31, 2017, and 2016 consist of:      Pension OPEB  Millions 2017 2016 2017 2016  Noncurrent assets $ 196 $ 67 $ - $ -  Current liabilities (27) (24) (23) (24)  Noncurrent liabilities (474) (405) (307) (310)  Net amounts recognized at end of year $ (305) $ (362) $ (330) $ (334) 
Schedule Of Pre-Tax Amounts Recognized In Accumulated Other Comprehensive Income/(Loss)	Pre-tax amounts recognized in accumulated other comprehensive income/(loss) as of December 31, 2017, and 2016 consist of:      2017 2016  Millions Pension OPEB Total Pension OPEB Total  Prior service cost $ - $ (1) $ (1) $ - $ (2) $ (2)  Net actuarial loss (1,533) (120) (1,653) (1,681) (123) (1,804)  Total $ (1,533) $ (121) $ (1,654) $ (1,681) $ (125) $ (1,806) 
Schedule Of Other Pre-Tax Changes Recognized In Other Comprehensive Income	Pre-tax changes recognized in other comprehensive inco me/(loss) during 2017, 2016, and 2015 were as follows:      Pension OPEB  Millions 2017 2016 2015 2017 2016 2015  Net actuarial (loss)/gain $ 67 $ (112) $ (31) $ (6) $ (16) $ 18  Amortization of:  Prior service cost/(credit) - - - 1 (9) (10)  Actuarial loss 81 83 106 9 10 13  Total $ 148 $ (29) $ 75 $ 4 $ (15) $ 21 
Amounts Included In Accumulated Other Comprehensive Income Expected To Be Amortized Into Net Periodic Cost (Benefit)	Amounts included in accumulated other comprehensive income/(loss) expected to be amortized into net periodic cost during 2018 :      Millions Pension OPEB Total  Prior service credit $ - $ (1) $ (1)  Net actuarial loss (90) (9) (99)  Total $ (90) $ (10) $ (100) 
Schedule Of Underfunded Accumulated Benefit Obligation	The following table discloses only the PBO, ABO, and fair value of plan assets for pension plans where the accumulated benefit obligation is in excess of the fair value of the plan assets as of December 31 :      Underfunded Accumulated Benefit Obligation  Millions 2017 2016  Projected benefit obligation $ 501 $ 428  Accumulated benefit obligation $ 481 $ 412  Fair value of plan assets - -  Underfunded accumulated benefit obligation $ (481) $ (412) 
Weighted-Average Actuarial Assumptions Used To Determine Benefit Obligations And Expense	The weighted-average actuarial assumptions used to determine benefit obligations at December 31:      Pension OPEB  Percentages 2017 2016 2017 2016  Discount rate 3.62% 4.20% 3.53% 4.00%  Compensation increase 4.20% 4.20% N/A N/A  Health care cost trend rate (employees under 65) N/A N/A 6.09% 6.31%  Ultimate health care cost trend rate N/A N/A 4.50% 4.50%  Year ultimate trend rate reached N/A N/A 2038 2038  The weighted-average actuarial assumptions used to determine expense were as follows:       Pension OPEB  Percentages 2017 2016 2015 2017 2016 2015  Discount rate for benefit obligations 3.80% 4.37% 3.94% 3.69% 4.13% 3.74%  Discount rate for interest on benefit obligations 3.30% 3.65% 3.94% 3.08% 3.34% 3.74%  Discount rate for service cost 4.01% 4.69% 3.94% 3.95% 4.59% 3.74%  Discount rate for interest on service cost 3.93% 4.55% 3.94% 3.85% 4.44% 3.74%  Expected return on plan assets 7.00% 7.50% 7.50% N/A N/A N/A  Compensation increase 4.20% 4.20% 4.00% N/A N/A N/A  Health care cost trend rate (employees under 65) N/A N/A N/A 6.31% 6.52% 6.34%  Ultimate health care cost trend rate N/A N/A N/A 4.50% 4.50% 4.50%  Year ultimate trend reached N/A N/A N/A 2038 2038 2028 
Net Periodic Pension And OPEB Cost/(Benefit)	The components of our net periodic pension and OPEB cost were as follows for the years ended December 31:      Pension OPEB  Millions 2017 2016 2015 2017 2016 2015  Net Periodic Benefit Cost:  Service cost $ 90 $ 84 $ 106 $ 2 $ 1 $ 3  Interest cost 142 143 163 10 11 13  Expected return on plan assets (267) (267) (255) - - - Plan curtailment cost 20 - - - - -  Special termination cost 49 - - - - -  Amortization of:  Prior service cost/(credit) - - - 1 (9) (10)  Actuarial loss 81 83 106 9 10 13  Net periodic benefit cost $ 115 $ 43 $ 120 $ 22 $ 13 $ 19  
OPEB Effects From One-Percentage Point Change Assumed Healthcare Cost Trend Rates	A one-percentage point change in the assumed health care cost trend rates would have the following effects on OPEB:      Millions One % pt. Increase One % pt. Decrease  Effect on total service and interest cost components $ 1 $ (1)  Effect on accumulated benefit obligation 19 (16) 
Cash Contributions For Qualified Pension Plan Benefit Payments For Non-Qualified OPEB Plans	The following table details our cash contributions for the qualified pension plans and the benefit payments for the non-qualified (supplemental) pension and OPEB plans:      Pension  Millions Qualified Non-qualified OPEB  2017 $ - $ 24 $ 22  2016 100 24 23 
Schedule Of Expected Benefit Payments	The following table details expected benefit payments for the years 2018 through 2027 :      Millions Pension OPEB  2018 $ 212 $ 23  2019 212 22  2020 211 22  2021 212 21  2022 213 20  Years 2023 - 2027 1,101 90 
Schedule Of Pension Plan Asset Allocation	Our pension plan asset allocation at December 31, 2017, and 2016 , and target allocation for 2018 , are as follows:      Percentage of Plan Assets  Target December 31,  Allocation 2018 2017 2016  Equity securities 60% to 70% 69% 68%  Debt securities 20% to 30% 22 21  Real estate 2% to 8% 5 6  Commodities 4% to 6% 4 5  Total 100% 100% 
Schedule Of Assets Measured At Fair Value On A Recurring Basis	As of December 31, 2017 , the pension plan assets measured at fair value on a recurring basis were as follows:       Quoted Prices Significant  in Active Other Significant  Markets for Observable Unobservable  Identical Inputs Inputs Inputs  Millions (Level 1) (Level 2) (Level 3) Total  Plan assets at fair value:  Temporary cash investments $ 27 $ $ - $ 27  Registered investment companies [a] 4 - 4  Federal government securities 182 - 182  Bonds and debentures 389 - 389  Corporate stock 1,171 8 - 1,179  Total plan assets at fair value $ 1,202 $ 579 $ - $ 1,781  Plan assets at NAV:  Registered investment companies [b] 329  Venture capital and buyout partnerships 358  Real estate partnerships 226  Collective trust and other funds 1,552  Total plan assets at NAV $ 2,465  Other assets [c] (22)  Total plan assets $ 4,224  [a] Registered investment companies measured at fair val ue include stock investments. [b] Registered investment companies measured at NAV include bond investments. [c] Other assets include accrued receivables , net payables, and pending broker settlements.  As of December 31, 2016 , the pension plan assets measured at fair value on a recurring basis were as follows:      Quoted Prices Significant  in Active Other Significant  Markets for Observable Unobservable  Identical Inputs Inputs Inputs  Millions (Level 1) (Level 2) (Level 3) Total  Plan assets at fair value:  Temporary cash investments $ 27 $ - $ - $ 27  Registered investment companies [a] 17 - - 17  Federal government securities - 142 - 142  Bonds and debentures - 357 - 357  Corporate stock 1,059 8 - 1,067  Total plan assets at fair value $ 1,103 $ 507 $ - $ 1,610  Plan assets at NAV:  Registered investment companies [b] 280  Venture capital and buyout partnerships 283  Real estate partnerships 212  Collective trust and other funds 1,346  Total plan assets at NAV $ 2,121  Other assets [c] 17  Total plan assets $ 3,748  [a] Registered investment companies measured at fair value include stock and real estate investments. [b] Registered investment companies measured at NAV include bond investments. [c] Other assets include accrued receivables and pending broker settlements.

Other Income (Tables)

Other Income (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income [Abstract]
Other Income	Other income included the following for the years ended December 31:      Millions 2017 2016 2015  Rental income [a] $ 178 $ 96 $ 96  Net gain on non-operating asset dispositions [b] [c] 111 94 144  Interest income 16 11 5  Non-operating environmental costs and other (15) (9) (19)  Total $ 290 $ 192 $ 226  [a] 2017 includes $65 million related to a favorable litigation settlement . [b] 2017 includes $26 million and $57 million related to a real estate sale in the first quarter and in the third quarter , respectively . [c] 2016 includes $17 million and $50 million related to a real estate sale in the first quarter and second quarter , respectively .

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Schedule Of Components Of Income Tax Expense	Components of income tax expense were as follows for the years ended December 31:      Millions 2017 2016 2015  Current tax expense:  Federal $ 1,750 $ 1,518 $ 1,901  State 235 176 210  Foreign 2 8 8  Total current tax expense 1,987 1,702 2,119  Deferred and other tax expense:  Federal (5,260) 692 644  State 183 139 121  Foreign 10 - -  Total deferred and other tax expense [a] (5,067) 831 765  Total income tax expense $ (3,080) $ 2,533 $ 2,884 
Reconciliations Between Statutory And Effective Tax Rates	For the years ended December 31, reconciliations between statutory and effective tax rates are as follows:      Tax Rate Percentages 2017 2016 2015  Federal statutory tax rate 35.0 % 35.0 % 35.0 %  State statutory rates, net of federal benefits 3.1 3.1 3.1  Adjustment for Tax Cuts and Jobs Act (77.8) - -  Other deferred tax adjustments 0.4 - -  Tax credits 0.1 (0.5) (0.5)  Other (1.2) (0.2) 0.1  Effective tax rate (40.4) % 37.4 % 37.7 % 
Schedule Of Deferred Income Tax Liabilities And Assets	Deferred income tax (liabilities)/assets were comprised of the following at December 31:      Millions 2017[a] 2016  Deferred income tax liabilities:  Property $ (11,262) $ (16,687)  Other (197) (346)  Total deferred income tax liabilities (11,459) (17,033)  Deferred income tax assets:  Accrued wages 46 75  Accrued casualty costs 147 231  Stock compensation 46 69  Retiree benefits 141 222  Credits 1 145  Other 142 295  Total deferred income tax assets $ 523 $ 1,037  Net deferred income tax liability $ (10,936) $ (15,996) 
Reconciliation Of Changes In Unrecognized Tax Benefits Liabilities/(Assets)	A reconciliation of changes in unrecognized tax benefits liabilities/(assets) from the beginning to the end of the reporting period is as follows:      Millions 2017 2016 2015  Unrecognized tax benefits at January 1 $ 125 $ 94 $ 151  Increases for positions taken in current year 38 31 38  Increases for positions taken in prior years 51 10 13  Decreases for positions taken in prior years (56) (20) (87)  Refunds from/(payments to) and settlements with taxing authorities 64 4 (13)  Increases/(decreases) for interest and penalties - 6 (5)  Lapse of statutes of limitations (43) - (3)  Unrecognized tax benefits at December 31 $ 179 $ 125 $ 94 
Unrecognized Tax Benefits That Would/Not Reduce The Effective Tax Rate	Several state tax authorities are examining our state income tax returns for years 2010 through 2015.  We do not expect our unrecognized tax benefits to change significantly in the next 12 months.  The portion of our unrecognized tax benefits that relates to permanent changes in tax and interest would reduce our effective tax rate, if recognized. The remaining unrecognized tax benefits relate to tax positions for which only the timing of the benefit is uncertain. Recognition of the tax benefits with uncertain timing would reduce our effective tax rate only through a reduction of accrued interest and penalties. The unrecognized tax benefits that would reduce our effective tax rate are as follows:             Millions 2017 2016 2015  Unrecognized tax benefits that would reduce the effective tax rate $ 83 $ 31 $ 31  Unrecognized tax benefits that would not reduce the effective tax rate 96 94 63  Total unrecognized tax benefits $ 179 $ 125 $ 94 

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Reconciliation Between Earnings Per Share	The following table provides a reconciliation between basic and diluted earnings per share for the years ended December 31:      Millions, Except Per Share Amounts 2017 2016 2015  Net income $ 10,712 $ 4,233 $ 4,772  Weighted-average number of shares outstanding:  Basic 798.4 832.4 866.2  Dilutive effect of stock options 1.8 1.5 1.5  Dilutive effect of retention shares and units 1.5 1.5 1.7  Diluted 801.7 835.4 869.4  Earnings per share – basic $ 13.42 $ 5.09 $ 5.51  Earnings per share – diluted $ 13.36 $ 5.07 $ 5.49 

Accumulated Other Comprehensi41

Accumulated Other Comprehensive Income/(Loss) (Tables)	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Income/(Loss) [Abstract]
After-Tax Components Of Accumulated Other Comprehensive Loss	Reclassifications out of accumulated other comprehensive income/(loss) were as follows (net of tax):      Millions Defined benefit plans Foreign currency translation Total  Balance at January 1, 2017 $ (1,132) $ (140) $ (1,272)  Other comprehensive income/(loss) before reclassifications 2 28 30  Amounts reclassified from accumulated other comprehensive income/(loss) [a] 101 - 101  Net year-to-date other comprehensive income/(loss), net of taxes of $(61) million 103 28 131  Balance at December 31, 2017 $ (1,029) $ (112) $ (1,141)   Balance at January 1, 2016 $ (1,103) $ (92) $ (1,195)  Other comprehensive income/(loss) before reclassifications (3) (48) (51)  Amounts reclassified from accumulated other comprehensive income/(loss) [a] (26) - (26)  Net year-to-date other comprehensive income/(loss), net of taxes of $49 million (29) (48) (77)  Balance at December 31, 2016 $ (1,132) $ (140) $ (1,272)  [a] The accumulated other comprehensive income/(loss) reclassification components are 1) prior service cost/(benefit) and 2) net actuarial loss which are both included in the computation of net periodic pension cost. See Note 6 Retirement Plans for additional details.

Properties (Tables)

Properties (Tables)	12 Months Ended
	Dec. 31, 2017
Properties [Abstract]
Schedule Of Properties	The following tables list the major categories of property and equipment, as well as the weighted-average estimated useful life for each category (in years):      Millions, Except Estimated Useful Life Accumulated Net Book Estimated  As of December 31, 2017 Cost Depreciation Value Useful Life  Land $ 5,258 $ N/A $ 5,258 N/A  Road:  Rail and other track material 16,327 5,929 10,398 43  Ties 10,132 2,881 7,251 33  Ballast 5,406 1,509 3,897 34  Other roadway [a] 18,972 3,482 15,490 47  Total road 50,837 13,801 37,036 N/A  Equipment:  Locomotives 9,686 3,697 5,989 19  Freight cars 2,255 983 1,272 24  Work equipment and other 936 267 669 19  Total equipment 12,877 4,947 7,930 N/A  Technology and other 1,105 460 645 11  Construction in progress 736 - 736 N/A  Total $ 70,813 $ 19,208 $ 51,605 N/A        Millions, Except Estimated Useful Life Accumulated Net Book Estimated  As of December 31, 2016 Cost Depreciation Value Useful Life  Land $ 5,220 $ N/A $ 5,220 N/A  Road:  Rail and other track material 15,845 5,722 10,123 40  Ties 9,812 2,736 7,076 33  Ballast 5,242 1,430 3,812 34  Other roadway [a] 18,138 3,226 14,912 47  Total road 49,037 13,114 35,923 N/A  Equipment:  Locomotives 9,692 3,939 5,753 20  Freight cars 2,243 972 1,271 24  Work equipment and other 905 232 673 19  Total equipment 12,840 5,143 7,697 N/A  Technology and other 974 412 562 11  Construction in progress 987 - 987 N/A  Total $ 69,058 $ 18,669 $ 50,389 N/A  [a] Other roadway includes grading, bridges and tunnels, signals, buildings, and other road assets.

Accounts Payable And Other Cu43

Accounts Payable And Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Accounts Payable And Other Current Liabilties [Abstract]
Schedule Of Accounts Payable And Other Current Liabilities	   Dec. 31, Dec. 31,  Millions 2017 2016  Accounts payable $ 1,013 $ 955  Income and other taxes payable 547 472  Accrued wages and vacation 384 387  Interest payable 220 212  Accrued casualty costs 194 185  Equipment rents payable 110 101  Other 671 570  Total accounts payable and other current liabilities $ 3,139 $ 2,882 

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt [Abstract]
Schedule Of Debt	Total debt as of December 31, 2017, and 2016 , is summarized below:      Millions 2017 2016  Notes and debentures, 1.8% to 7.9% due through 2067 $ 15,096 $ 13,547  Capitalized leases, 3.1% to 8.4% due through 2028 892 1,105  Equipment obligations, 2.6% to 6.7% due through 2031 1,018 1,069  Term loans - floating rate, due in 2018 250 100  Mortgage bonds, 4.8% due through 2030 57 57  Medium-term notes, 9.3% to 10.0% due through 2020 18 23  Receivables Securitization (Note 11) 500 -  Unamortized discount and deferred issuance costs (887) (894)  Total debt 16,944 15,007  Less: current portion (800) (758)  Total long-term debt $ 16,144 $ 14,249 
Aggregate Debt Maturities	The following table presents aggregate debt maturities as of December 31, 2017 , excluding market value adjustments:      Millions  2018 $ 806  2019 1,125  2020 1,021  2021 677  2022 917  Thereafter 13,285  Total principal 17,831  Unamortized discount and deferred issuance costs (887)  Total debt $ 16,944 
Unsecured Fixed Rate Debt Securities Issued Under Current Shelf Registration	During 2017 , we issued the following unsecured, fixed-rate debt securities under our current shelf registration:      Date Description of Securities  April 5, 2017 $500 million of 3.000% Notes due April 15, 2027  $500 million of 4.000% Notes due April 15, 2047  September 19, 2017 $500 million of 3.600% Notes due September 15, 2037  $500 million of 4.100% Notes due September 15, 2067 

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Future Minimum Lease Payments For Operating And Capital Leases	Future minimum lease payments for operating and capital leases with initial or remaining non-cancelable lease terms in excess of one year as of December 31, 2017 , were as follows:      Millions Operating Leases Capital Leases  2018 $ 398 $ 173  2019 359 156  2020 297 164  2021 259 168  2022 221 147  Later years 1,115 271  Total minimum lease payments $ 2,649 $ 1,079  Amount representing interest N/A (187)  Present value of minimum lease payments N/A $ 892 

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies [Abstract]
Commitments And Contingencies Activity	Our personal injury liability activity was as follows:      Millions 2017 2016 2015  Beginning balance $ 290 $ 318 $ 335  Current year accruals 77 75 89  Changes in estimates for prior years (7) (29) (3)  Payments (75) (74) (103)  Ending balance at December 31 $ 285 $ 290 $ 318  Current portion, ending balance at December 31 $ 66 $ 62 $ 63  Our asbestos-related liability activity was as follows:      Millions 2017 2016 2015  Beginning balance $ 111 $ 120 $ 126  Accruals/(Credits) (1) 12 -  Payments (11) (21) (6)  Ending balance at December 31 $ 99 $ 111 $ 120  Current portion, ending balance at December 31 $ 9 $ 8 $ 6  Our environmental liability activity was as follows:      Millions 2017 2016 2015  Beginning balance $ 212 $ 190 $ 182  Accruals 45 84 61  Payments (61) (62) (53)  Ending balance at December 31 $ 196 $ 212 $ 190  Current portion, ending balance at December 31 $ 57 $ 55 $ 52 

Share Repurchase Program (Table

Share Repurchase Program (Tables)	12 Months Ended
	Dec. 31, 2017
Share Repurchase Program [Abstract]
Share Repurchase Program	The table below represents shares repurchased in 2017 under this repurchase program and shares repurchased in 2016 under our previous repurchase program.      Number of Shares Purchased Average Price Paid  2017 2016 2017 2016  First quarter 7,531,300 9,315,807 $ 106.55 $ 76.49  Second quarter 7,788,283 7,026,100 109.10 85.66  Third quarter 11,801,755 9,088,613 106.69 93.63  Fourth quarter 9,231,510 9,624,667 119.37 97.60  Total 36,352,848 35,055,187 $ 110.40 $ 88.57 

Selected Quarterly Data (Unau48

Selected Quarterly Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Data (Unaudited) [Abstract]
Selected Quarterly Data (Unaudited)	   Millions, Except Per Share Amounts  2017 Mar. 31 Jun. 30 Sep. 30 Dec. 31  Operating revenues $ 5,132 $ 5,250 $ 5,408 $ 5,450  Operating income 1,793 2,005 2,012 2,251  Net income 1,072 1,168 1,194 7,278  Net income per share:  Basic 1.32 1.45 1.50 9.29  Diluted 1.32 1.45 1.50 9.25      Millions, Except Per Share Amounts  2016 Mar. 31 Jun. 30 Sep. 30 Dec. 31  Operating revenues $ 4,829 $ 4,770 $ 5,174 $ 5,168  Operating income 1,687 1,660 1,960 1,965  Net income 979 979 1,131 1,144  Net income per share:  Basic 1.16 1.17 1.36 1.40  Diluted 1.16 1.17 1.36 1.39 

Nature Of Operations (Details)

Nature Of Operations (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)mi	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)segmentmi	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Commodity Group Information [Line Items]
Freight revenues									$ 19,837	$ 18,601	$ 20,397
Other revenues									1,403	1,340	1,416
Total operating revenues	$ 5,450	$ 5,408	$ 5,250	$ 5,132	$ 5,168	$ 5,174	$ 4,770	$ 4,829	$ 21,240	19,941	21,813
Network route miles | mi	32,122								32,122
Route miles owned | mi	26,042								26,042
Reportable segments | segment									1
Agricultural Products [Member]
Commodity Group Information [Line Items]
Freight revenues									$ 3,685	3,625	3,581
Automotive [Member]
Commodity Group Information [Line Items]
Freight revenues									1,998	2,000	2,154
Chemicals [Member]
Commodity Group Information [Line Items]
Freight revenues									3,596	3,474	3,543
Coal [Member]
Commodity Group Information [Line Items]
Freight revenues									2,645	2,440	3,237
Industrial Products [Member]
Commodity Group Information [Line Items]
Freight revenues									4,078	3,348	3,808
Intermodal [Member]
Commodity Group Information [Line Items]
Freight revenues									3,835	3,714	4,074
Mexico [Member]
Commodity Group Information [Line Items]
Freight revenues									$ 2,300	$ 2,200	$ 2,200

Accounting Pronouncements (Deta

Accounting Pronouncements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restructuring Charges	$ 86
Other nonoperating income expense	290	$ 192	$ 226
Pension, [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restructuring Charges	69
ASU 2017-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase/(decrease) in operating income	45	(29)	30
Increase/(decrease) in other income	(45)	$ 29	$ (30)
ASU 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in assets and liabilities	$ 2,000

Workforce Reduction Plan (Detai

Workforce Reduction Plan (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)item
Restructuring Cost and Reserve [Line Items]
Compensation and benefits expense	$ 86
Agreement Positions [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | item	250
Management Positions [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | item	460
Pension. [Member]
Restructuring Cost and Reserve [Line Items]
Compensation and benefits expense	$ 69
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Compensation and benefits expense	12
Equity Compensation [Member]
Restructuring Cost and Reserve [Line Items]
Compensation and benefits expense	$ 5

Stock Options And Other Stock52

Stock Options And Other Stock Plans (Narrative) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Share-based Compensation Arrangements [Line Items]
Shares of common stock authorized and available	72,151,415	73,745,250	76,548,520
Union Pacific Corporation 2000 Directors Plan [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Stock options, shares outstanding	0
Restricted shares outstanding	44,000
Common stock reserved for issuance	2,200,000
Initial grant of retention stock share/units description	Under the Directors Plan, each non-employee director, upon his or her initial election to the Board of Directors, receives a grant of 4,000 retention shares or retention stock units. Prior to December 31, 2007, each non-employee director received annually an option to purchase at fair value a number of shares of our common stock, not to exceed 20,000 shares during any calendar year, determined by dividing 60,000 by 1/3 of the fair market value of one share of our common stock on the date of such Board of Directors meeting, with the resulting quotient rounded up or down to the nearest 50 shares.
Union Pacific Corporation 2004 Stock Incentive Plan [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Stock options, shares outstanding	1,557,350
Retention shares and stock units outstanding	962
Common stock reserved for issuance	84,000,000
Union Pacific Corporation 2013 Stock Incentive Plan [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Stock options, shares outstanding	4,072,514
Retention shares and stock units outstanding	3,450,600
Common stock reserved for issuance	78,000,000

Stock Options And Other Stock53

Stock Options And Other Stock Plans (Stock Options, Retention Awards And Performance Retention Awards) (Narrative) (Details) $ / shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)$ / shares
Stock Options [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Contractual term	10 years
Years until vest	3 years
Stock options, subject to performance or market-based vesting conditions | $ / shares	$ 0
Unrecognized compensation expense	$ 19
Expected weighted average period (in years) of nonvested stock options to be recognized	1 year 1 month 6 days
Retention Awards [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Years until vest	4 years
Unrecognized compensation expense	$ 87
Expected weighted average period (in years) of nonvested stock options to be recognized	1 year 7 months 6 days
Performance Retention Awards [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Operating income growth modifier range	The modifier can be up to +/- 25% of the award earned based on the ROIC achieved.
Requisite service period	37 months
Continued employment requirement	Stock units awarded to selected employees under these grants are subject to continued employment for 37 months and the attainment of certain levels of ROIC, and for the 2016 and 2017 plans, modified for the relative OIG.
Contractual terms of award	We expense the fair value of the units that are probable of being earned based on our forecasted ROIC over the 3-year performance period, and with respect to the third year of the 2016 and 2017 plans, the relative OIG modifier.
ROIC performance period	3 years
Unrecognized compensation expense	$ 39
Expected weighted average period (in years) of nonvested stock options to be recognized	1 year 6 months

Stock-based Compensation (Sched

Stock-based Compensation (Schedule Of Stock-Based Compensation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation, Before Tax: [Abstract]
Stock options	$ 19	$ 16	$ 17
Retention awards	84	66	81
Total stock-based compensation, before tax	103	82	98
Excess tax benefits from equity compensation plans, financing activities		$ 28	$ 62
Excess tax benefits from equity compensation plans, operating activities	$ 44

Stock-based Compensation (Sch55

Stock-based Compensation (Schedule Of Stock Options Weighted Average Assumptions) (Details) - Stock Options [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assumptions For Stock Awards [Abstract]
Risk-free interest rate	2.00%	1.30%	1.30%
Dividend yield	2.30%	2.90%	1.80%
Expected life (years)	5 years 3 months 18 days	5 years 1 month 6 days	5 years 1 month 6 days
Volatility	21.70%	23.20%	23.40%
Weighted-average grant-date fair value of options granted	$ 18.19	$ 11.36	$ 22.30

Stock-based Compensation (Summa

Stock-based Compensation (Summary Of Stock Option Activities) (Details) - Stock Options [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Schedule of Share-based Compensation Arrangements [Line Items]
Stock options, shares outstanding at January 1, 2017	6,162
Stock options, shares granted	1,086
Stock options, shares exercised	(1,448)
Stock options, shares forfeited or expired	(170)
Stock options, shares outstanding at December 31, 2017	5,630	6,162
Stock options, shares vested or expected to vest at December 31, 2017	5,607
Stock options, shares exercisable at December 31, 2017	3,466
Stock options weighted-average exercise price, outstanding at January 1, 2017	$ 73.13
Stock options weighted-average exercise price, granted	107.30
Stock options weighted-average exercise price, exercised	56.69
Stock options weighted-average exercise price, forfeited or expired	92.18
Stock options weighted-average exercise price, outstanding at December 31, 2017	83.37	$ 73.13
Stock options weighted-average exercise price, vested or expected to vest at December 31, 2017	83.25
Stock options weighted-average exercise price, options exercisable at December 31, 2017	$ 75.96
Stock options weighted-average remaining contractual term in years, outstanding at January 1, 2017		5 years 10 months 24 days
Stock options weighted-average remaining contractual term in years, outstanding at December 31, 2017	5 years 9 months 18 days
Stock options weighted-average remaining contractual term in years, vested or expected to vest at December 31, 2017	5 years 9 months 18 days
Stock options weighted-average remaining contractual term in years, options exercisable at December 31, 2017	4 years 2 months 12 days
Stock options aggregate intrinsic value, outstanding at January 1, 2017	$ 205
Stock options aggregate intrinsic value, outstanding at December 31, 2017	286	$ 205
Stock options aggregate intrinsic value, vested or expected to vest at December 31, 2017	285
Stock options aggregate intrinsic value, options exercisable at December 31, 2017	$ 201

Stock-based Compensation (Sch57

Stock-based Compensation (Schedule Of Stock Option Exercises) (Details) - Stock Options [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Option Aggregate Disclosures [Abstract]
Intrinsic value of stock options exercised	$ 88	$ 52	$ 50
Cash received from option exercises	59	39	27
Treasury shares repurchased for employee payroll taxes	(18)	(15)	(12)
Tax benefit realized from option exercises	34	20	19
Aggregate grant-date fair value of stock options vested	$ 20	$ 19	$ 19

Stock-based Compensation (Sch58

Stock-based Compensation (Schedule Of Retention Awards) (Details) - Retention Awards [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Schedule of Share-based Compensation Arrangements [Line Items]
Awards, shares nonvested at January 1, 2017 | shares	2,789
Awards, shares granted | shares	575
Awards, shares vested | shares	(894)
Awards, shares forfeited | shares	(157)
Awards, shares nonvested at December 31, 2017 | shares	2,313
Awards weighted-average grant-date fair value, nonvested at January 1, 2017 | $ / shares	$ 84.68
Awards weighted-average grant-date fair value, granted | $ / shares	107.51
Awards weighted-average grant-date fair value, vested | $ / shares	70.91
Awards weighted-average grant-date fair value, forfeited | $ / shares	94.01
Awards weighted-average grant-date fair value, nonvested at December 31, 2017 | $ / shares	$ 95.04

Stock-based Compensation (Perfo

Stock-based Compensation (Performance Retention Awards, Present Value Calculation Assumptions) (Details) - Performance Retention Awards [Member]	12 Months Ended
	Dec. 31, 2017$ / shares
Assumptions For Stock Awards [Abstract]
Dividend per share per quarter	$ 0.605
Risk-free interest rate at date of grant	1.50%

Stock-based Compensation (Sch60

Stock-based Compensation (Schedule Of Performance Retention Awards) (Details) - Performance Retention Awards [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Schedule of Share-based Compensation Arrangements [Line Items]
Awards, shares nonvested at January 1, 2017 | shares	1,145
Awards, shares granted | shares	461
Awards, shares vested | shares	(255)
Awards, shares unearned | shares	(110)
Awards, shares forfeited | shares	(103)
Awards, shares nonvested at December 31, 2017 | shares	1,138
Awards weighted-average grant-date fair value, nonvested at January 1, 2017 | $ / shares	$ 86.23
Awards weighted-average grant-date fair value, granted | $ / shares	101.38
Awards weighted-average grant-date fair value, vested | $ / shares	83.06
Awards weighted-average grant-date fair value, unearned | $ / shares	83.06
Awards weighted-average grant-date fair value, forfeited | $ / shares	91.36
Awards weighted-average grant-date fair value, nonvested at December 31, 2017 | $ / shares	$ 92.92

Retirement Plans (Narrative) (D

Retirement Plans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)	Dec. 31, 2015
Retirement Plans [Line Items]
Pension & OPEB Descriptions		Pension Plans – We provide defined benefit retirement income to eligible non-union employees through qualified and non-qualified (supplemental) pension plans. Qualified and non-qualified pension benefits are based on years of service and the highest compensation during the latest years of employment, with specific reductions made for early retirements. Non-union employees hired on or after January 1, 2018, are no longer eligible for pension benefits, but will be eligible for an enhanced 401(k) plan as described below in other retirement programs. Other Postretirement Benefits (OPEB) – We provide medical and life insurance benefits for eligible retirees hired before January 1, 2004. These benefits are funded as medical claims and life insurance premiums are paid.
Changes in fair value period		5 years
Curtailment cost		$ 20,000,000
Special termination cost		$ 49,000,000
Discount rate - benefit obligations		3.81%	4.20%
Significant transfers in or out of Levels 1, 2, or 3		$ 0	$ 0
Pension Plan Master Trust future commitments for additonal contributions private equtiy partnerships		359,000,000	392,000,000
Pension Plan Master Trust future commitments for additional contributions real estate partnerships and funds		$ 67,000,000	32,000,000
Management Positions. [Member]
Retirement Plans [Line Items]
Number of positions eliminated | item		460
Pension [Member]
Retirement Plans [Line Items]
Accumulated benefit obligation		$ 481,000,000	412,000,000
Accumulated benefit obligation.		4,200,000,000	$ 3,900,000,000
Curtailment cost		20,000,000
Special termination cost		$ 49,000,000
Discount rate - benefit obligations		3.62%	4.20%
Actual return (loss) on pension plan assets, net of fees		19.00%	8.00%	(1.00%)
OPEB [Member]
Retirement Plans [Line Items]
Curtailment cost		$ (1,000,000)
Discount rate - benefit obligations		3.53%	4.00%
Health care cost trend rate (employees under 65)		6.31%	6.52%	6.34%
Ultimate health care cost trend rate		4.50%	4.50%	4.50%
Year ultimate trend rate reached		2,038	2,038	2,028
OPEB [Member] | 2018 Forecast [Member]
Retirement Plans [Line Items]
Health care cost trend rate (employees under 65)	6.09%
Ultimate health care cost trend rate	4.50%
Year ultimate trend rate reached	2,038
Pension Non-qualified Plan [Member]
Retirement Plans [Line Items]
Accumulated benefit obligation		$ 481,000,000	$ 412,000,000

Retirement Plans (Other Retirem

Retirement Plans (Other Retirement Programs) (Narrative) (Details) - USD ($) $ in Millions	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
401(k)/Thrift Plan [Abstract]
401(k)/Thrift plan description		For non-union employees hired prior to January 1, 2018, and eligible union employees for whom we make matching contributions, we provide a defined contribution plan (401(k)/thrift plan).
401(k)/Thrift plan contributions		$ 19	$ 19	$ 20
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		50.00%
Railroad Retirement System [Abstract]
Railroad Retirement System description		All Railroad employees are covered by the Railroad Retirement System (the System).
Railroad Retirement System contributions		$ 672	671	749
Subsequent Event [Member]
401(k)/Thrift Plan [Abstract]
401(k)/Thrift plan description	For non-union employees hired on or after January 1, 2018, we provide a defined contribution plan (401(k))/thrift plan).
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100.00%
Defined contribution plan, additional annual employer contribution, percent of employee's gross pay	3.00%
Collective Bargaining Agreements [Member]
Collective Bargaining Agreements [Abstract]
Collective bargaining agreements description		Under collective bargaining agreements, we participate in multi-employer benefit plans that provide certain postretirement health care and life insurance benefits for eligible union employees.
Collective bargaining agreements premiums		$ 60	$ 50	$ 46

Retirement Plans (Schedule Of C

Retirement Plans (Schedule Of Changes In Projected Benefit Obligation And Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Projected Benefit Obligation [Abstract]
Curtailment cost	$ 20
Special termination cost	49
Pension [Member]
Projected Benefit Obligation [Abstract]
Projected benefit obligation at beginning of year	4,110	$ 3,958
Service cost	90	84	$ 106
Interest cost	142	143	163
Curtailment cost	20
Special termination cost	49
Actuarial loss/(gain)	382	124
Gross benefits paid	(264)	(199)
Projected benefit obligation at end of year	4,529	4,110	3,958
Plan Assets [Abstract]
Fair value of plan assets at beginning of year	3,748	3,544
Actual return/(loss) on plan assets	716	279
Voluntary funded pension plan contributions		100
Non-qualified plan benefit contributions	24	24
Gross benefits paid	(264)	(199)
Fair value of plan assets at end of year	4,224	3,748	3,544
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status at end of year	(305)	(362)
OPEB [Member]
Projected Benefit Obligation [Abstract]
Projected benefit obligation at beginning of year	334	329
Service cost	2	1	3
Interest cost	10	11	13
Curtailment cost	(1)
Actuarial loss/(gain)	7	16
Gross benefits paid	(22)	(23)
Projected benefit obligation at end of year	330	334	329
Plan Assets [Abstract]
Fair value of plan assets at beginning of year
Actual return/(loss) on plan assets
Voluntary funded pension plan contributions
Non-qualified plan benefit contributions - OPEB	22	23
Gross benefits paid	(22)	(23)
Fair value of plan assets at end of year
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status at end of year	$ (330)	$ (334)

Retirement Plans (Schedule Of A

Retirement Plans (Schedule Of Amounts Recognized In Statement Of Financial Position) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Amounts recognized - noncurrent assets	$ 196	$ 67
Amounts recognized - current liabilities	(27)	(24)
Amounts recognized - noncurrent liabilities	(474)	(405)
Net amounts recognized at end of year	(305)	(362)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Amounts recognized - noncurrent assets
Amounts recognized - current liabilities	(23)	(24)
Amounts recognized - noncurrent liabilities	(307)	(310)
Net amounts recognized at end of year	$ (330)	$ (334)

Retirement Plans (Schedule Of P

Retirement Plans (Schedule Of Pre-Tax Amounts Recognized In Accumulated Other Comprehensive Income/(Loss)) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost)/credit	$ (1)	$ (2)
Net actuarial loss	(1,653)	(1,804)
Total pre-tax amounts recognized in accumulated other comprehensive income/(loss)	(1,654)	(1,806)
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost)/credit
Net actuarial loss	(1,533)	(1,681)
Total pre-tax amounts recognized in accumulated other comprehensive income/(loss)	(1,533)	(1,681)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost)/credit	(1)	(2)
Net actuarial loss	(120)	(123)
Total pre-tax amounts recognized in accumulated other comprehensive income/(loss)	$ (121)	$ (125)

Retirement Plans (Schedule Of O

Retirement Plans (Schedule Of Other Pre-Tax Changes Recognized In Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss)/gain - OCI	$ 67	$ (112)	$ (31)
Amortization of prior service cost/(credit) - OCI
Amortization of actuarial loss - OCI	81	83	106
Total other pre-tax changes recognized in other comprehensive income	148	(29)	75
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss)/gain - OCI	(6)	(16)	18
Amortization of prior service cost/(credit) - OCI	1	(9)	(10)
Amortization of actuarial loss - OCI	9	10	13
Total other pre-tax changes recognized in other comprehensive income	$ 4	$ (15)	$ 21

Retirement Plans (Amounts Inclu

Retirement Plans (Amounts Included In Accumulated Other Comprehensive Income Expected To Be Amortized Into Net Periodic Cost (Benefit)) (Details) - 2018 Forecast [Member] $ in Millions	Dec. 31, 2018USD ($)
Defined Benefit Plan Disclosure [Line Items]
Prior service credit - AOCI	$ (1)
Net actuarial loss - AOCI	(99)
Total amounts included in accumulated other comprehensive income expected to be amortized into net periodic cost (benefit)	(100)
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service credit - AOCI
Net actuarial loss - AOCI	(90)
Total amounts included in accumulated other comprehensive income expected to be amortized into net periodic cost (benefit)	(90)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service credit - AOCI	(1)
Net actuarial loss - AOCI	(9)
Total amounts included in accumulated other comprehensive income expected to be amortized into net periodic cost (benefit)	$ (10)

Retirement Plans (Underfunded A

Retirement Plans (Underfunded Accumulated Benefit Obligation) (Details) - Pension [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Retirement Plans [Line Items]
Projected benefit obligation	$ 501	$ 428
Accumulated benefit obligation	481	412
Fair value of plan assets
Underfunded accumulated benefit obligation	$ (481)	$ (412)

Retirement Plans (Weighted-Aver

Retirement Plans (Weighted-Average Actuarial Assumptions Used To Determine Benefit Obligations) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Discount rate - benefit obligations	3.81%	4.20%
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate - benefit obligations	3.62%	4.20%
Compensation increase - benefit obligations	4.20%	4.20%
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate - benefit obligations	3.53%	4.00%
Health care cost trend rate (employees under 65) - benefit obligations	6.09%	6.31%
Ultimate health care cost trend rate - benefit obligations	4.50%	4.50%
Year ultimate trend reached - benefit obligations	2,038	2,038

Retirement Plans (Net Periodic

Retirement Plans (Net Periodic Pension And OPEB Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Periodic Pension And OPEB Cost [Abstract]
Curtailment cost	$ 20
Special termination cost	49
Pension [Member]
Net Periodic Pension And OPEB Cost [Abstract]
Service cost	90	$ 84	$ 106
Interest cost	142	143	163
Expected return on plan assets	(267)	(267)	(255)
Curtailment cost	20
Special termination cost	49
Amortization of prior service cost/(credit)
Amortization of actuarial loss	81	83	106
Net periodic pension/OPEB cost	115	43	120
OPEB [Member]
Net Periodic Pension And OPEB Cost [Abstract]
Service cost	2	1	3
Interest cost	10	11	13
Expected return on plan assets
Curtailment cost	(1)
Amortization of prior service cost/(credit)	1	(9)	(10)
Amortization of actuarial loss	9	10	13
Net periodic pension/OPEB cost	$ 22	$ 13	$ 19

Retirement Plans (Weighted-Av71

Retirement Plans (Weighted-Average Actuarial Assumptions Used To Determine Benefit Expense) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	4.09%	4.37%	3.94%
Discount rate for interest on benefit obligations	3.47%	3.65%	3.94%
Discount rate for service cost	4.41%	4.69%	3.94%
Discount rate for interest on service cost	4.27%	4.55%	3.94%
Expected return on plan assets - expense	7.00%	7.50%	7.50%
Compensation increase - expense	4.13%	4.20%	4.00%
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	3.89%	4.13%	3.74%
Discount rate for interest on benefit obligations	3.25%	3.34%	3.74%
Discount rate for service cost	4.25%	4.59%	3.74%
Discount rate for interest on service cost	4.11%	4.44%	3.74%
Health care cost trend rate for next year (employees under 65) - expense	6.31%	6.52%	6.34%
Ultimate health care cost trend rate - expense	4.50%	4.50%	4.50%
Year ultimate trend rate reached - expense	2,038	2,038	2,028

Retirement Plans (OPEB Effects

Retirement Plans (OPEB Effects From One-Percentage Point Change Assumed Healthcare Cost Trend Rates) (Details) - OPEB [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
Effect on total service and interest cost components - one % pt. increase	$ 1
Effect on total service and interest cost components - one % pt. decrease	(1)
Effect on accumulated benefit obligation - one % pt. increase	19
Effect on accumulated benefit obligation - one % pt. decrease	$ (16)

Retirement Plans (Cash Contribu

Retirement Plans (Cash Contributions For Qualified Pension Plan Benefit Payments For Non-Qualified OPEB Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to qualified pension plan
Cash contribution to non-qualified OPEB plan	22	23
Pension Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to qualified pension plan		100
Pension Non-qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to non-qualified pension plan	$ 24	$ 24

Retirement Plans (Schedule Of E

Retirement Plans (Schedule Of Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2017USD ($)
Pension [Member]
Benefit Payments [Abstract]
2,018	$ 212
2,019	212
2,020	211
2,021	212
2,022	213
Years 2023 - 2027	1,101
OPEB [Member]
Benefit Payments [Abstract]
2,018	23
2,019	22
2,020	22
2,021	21
2,022	20
Years 2023 - 2027	$ 90

Retirement Plans (Schedule Of75

Retirement Plans (Schedule Of Pension Plan Asset Allocation) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	7.00%
Asset allocation	100.00%	100.00%
Average long-term rate of return target description	The investment strategy for pension plan assets is to maintain a broadly diversified portfolio designed to achieve our target average long-term rate of return of 7.0%.
Weighted-average maturity of Pension Plan debt portfolio	13 years	14 years
Prohibited investments description	The investment of pension plan assets in securities issued by UPC is explicitly prohibited by the plan for both the equity and debt portfolios, other than through index fund holdings.
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	69.00%	68.00%
Equity Securities [Member] | 2018 Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	60.00%
Equity Securities [Member] | 2018 Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	70.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	22.00%	21.00%
Debt Securities [Member] | 2018 Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	20.00%
Debt Securities [Member] | 2018 Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	30.00%
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	5.00%	6.00%
Real Estate [Member] | 2018 Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	2.00%
Real Estate [Member] | 2018 Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	8.00%
Commodities [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	4.00%	5.00%
Commodities [Member] | 2018 Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	4.00%
Commodities [Member] | 2018 Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target average rate of return	6.00%

Retirement Plans (Schedule Of76

Retirement Plans (Schedule Of Assets Measured At Fair Value On A Recurring Basis) (Details) - Pension [Member] - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 4,224	$ 3,748	$ 3,544
Temporary Cash Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		27	27
Registered Investment Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	4	17
Federal Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		182	142
Bonds and Debentures [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		389	357
Corporate Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,179	1,067
Total Plan Assets At Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,781	1,610
Registered Investment Companies - NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	329	280
Venture Capital And Buyout Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		358	283
Real Estate Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		226	212
Collective Trust And Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,552	1,346
Total Plan Assets at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2,465	2,121
Other Assets - Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	(22)	17
Quoted Prices in Active Markets for Identical Inputs (Level 1) [Member] | Temporary Cash Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		27	27
Quoted Prices in Active Markets for Identical Inputs (Level 1) [Member] | Registered Investment Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	4	17
Quoted Prices in Active Markets for Identical Inputs (Level 1) [Member] | Federal Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Quoted Prices in Active Markets for Identical Inputs (Level 1) [Member] | Bonds and Debentures [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Quoted Prices in Active Markets for Identical Inputs (Level 1) [Member] | Corporate Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,171	1,059
Quoted Prices in Active Markets for Identical Inputs (Level 1) [Member] | Total Plan Assets At Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,202	1,103
Significant Other Observable Inputs (Level 2) [Member] | Temporary Cash Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Other Observable Inputs (Level 2) [Member] | Registered Investment Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]
Significant Other Observable Inputs (Level 2) [Member] | Federal Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		182	142
Significant Other Observable Inputs (Level 2) [Member] | Bonds and Debentures [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		389	357
Significant Other Observable Inputs (Level 2) [Member] | Corporate Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		8	8
Significant Other Observable Inputs (Level 2) [Member] | Total Plan Assets At Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		579	507
Significant Unobservable Inputs (Level 3) [Member] | Temporary Cash Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Unobservable Inputs (Level 3) [Member] | Registered Investment Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]
Significant Unobservable Inputs (Level 3) [Member] | Federal Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Unobservable Inputs (Level 3) [Member] | Bonds and Debentures [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Unobservable Inputs (Level 3) [Member] | Corporate Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Unobservable Inputs (Level 3) [Member] | Total Plan Assets At Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
[1]	Registered investment companies measured at fair value include stock investments.
[2]	Registered investment companies measured at NAV include bond investments.
[3]	Other assets include accrued receivables, net payables, and pending broker settlements.

Other Income (Details)

Other Income (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Other Income [Abstract]
Rental income					$ 178	[1]	$ 96		$ 96
Net gain on non-operating asset dispositions.					111	[2]	94	[3]	144
Interest income					16		11		5
Non-operating environmental costs and other					(15)		(9)		(19)
Total					290		$ 192		$ 226
Gain (Loss) Related to Litigation Settlement					$ 65
Real estate sale	$ 57	$ 26	$ 50	$ 17
[1]	2017 includes $65 million related to a favorable litigation settlement.
[2]	2017 includes $26 million and $57 million related to a real estate sale in the first quarter and in the third quarter, respectively.
[3]	2016 includes $17 million and $50 million related to a real estate sale in the first quarter and second quarter, respectively.

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	Jan. 01, 2018	Sep. 30, 2017	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal statutory tax rate				35.00%	35.00%	35.00%
Tax Cuts and Jobs Act of 2017, deferred tax liability, income tax expense (benefit) total				$ (5,900)
Tax Cuts And Jobs Act of 2017, operating expense (benefit) from equity-method affiliates adjustments				(212)
Increase in deferred tax expense for increased tax rate		$ 33
Total accrued liabilities for interest and penalties				8	$ 8
Total interest and penalties recognized as part of income tax expense				$ (3)	$ 5	$ (3)
Taxes paid in connection to settlement			$ 10
Income tax examination refund		62
Income tax examination tax refund from settlement with taxing authority		60
Income tax examination interest refund from settlement with taxing authority		$ 2
Internal Revenue Service (IRS) [Member]
Federal statutory tax rate				35.00%
Tax Cuts and Jobs Act 2017 [Member] | Subsequent Event [Member]
Tax Cuts and Jobs Act of 2017, bonus depreciation on certain capital expenditures percentage	100.00%
Tax Cuts and Jobs Act 2017 [Member] | Internal Revenue Service (IRS) [Member] | Subsequent Event [Member]
Federal statutory tax rate	21.00%

Income Taxes (Schedule Of Compo

Income Taxes (Schedule Of Components Of Income Tax Expense) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Income Tax Expense [Abstract]
Current federal income tax expense		$ 1,750	$ 1,518	$ 1,901
Current state income tax expense		235	176	210
Current foreign income tax expense		2	8	8
Total current income tax expense		1,987	1,702	2,119
Deferred Income Tax Expense [Abstract]
Deferred federal income tax expense		(5,260)	692	644
Deferred state income tax expense		183	139	121
Deferred foreign income tax expense (benefit)		10
Total deferred income tax expense	[1]	(5,067)	831	765
Total income tax expense		(3,080)	$ 2,533	$ 2,884
Tax Cuts and Jobs Act of 2017, deferred tax liability, income tax expense (benefit) total		(5,935)
Tax Cuts and Jobs Act of 2017, federal income tax expense (benefit)		(5,965)
Tax Cuts and Jobs Act of 2017, state income tax expense (benefit)		$ 30
[1]	2017 includes a $(5,935) million adjustment to income tax expense resulting from the Tax Cuts and Jobs Act. Of this amount, $(5,965) million is a federal income tax benefit and $30 million is a state income tax expense.

Income Taxes (Reconciliations B

Income Taxes (Reconciliations Between Statutory And Effective Tax Rates) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation Between Statutory And Effective Tax Rates [Abstract]
Federal statutory tax rate	35.00%	35.00%	35.00%
State statutory rates, net of federal benefits	3.10%	3.10%	3.10%
Adjustment for Tax Cuts and Jobs Act	(77.80%)
Deferred tax adjustments	0.40%
Tax credits	0.10%	(0.50%)	(0.50%)
Other tax rate adjustments	(1.20%)	(0.20%)	0.10%
Effective tax rate	(40.40%)	37.40%	37.70%

Income Taxes (Schedule Of Defer

Income Taxes (Schedule Of Deferred Income Tax Liabilities And Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017		Dec. 31, 2016
Components Of Deferred Income Tax (Liabilities)/Assets [Abstract]
Deferred income tax liabilities - property	$ (11,262)	[1]	$ (16,687)
Deferred income tax liabilities - other	(197)	[1]	(346)
Total deferred income tax liabilities	(11,459)	[1]	(17,033)
Deferred income tax asset - accrued wages	46	[1]	75
Deferred income tax asset - accrued casualty costs	147	[1]	231
Deferred income tax asset - stock compensation	46	[1]	69
Deferred income tax asset - retiree benefits	141	[1]	222
Deferred income tax asset - credits	1	[1]	145
Deferred income tax asset - other	142	[1]	295
Total deferred income tax asset	523	[1]	1,037
Net deferred income tax liability	(10,936)	[1]	(15,996)
Income Tax Details [Abstract]
Deferred tax valuation allowance	$ 0		$ 0
[1]	2017 amounts reflect the provisional impact of the Tax Act.

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Changes In Unrecognized Tax Benefits Liabilities/(Assets)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation Of Changes In Unrecognized Tax Benefits Liabilities/(Assets) [Abstract]
Unrecognized tax benefits at January 1	$ 125	$ 94	$ 151
Increases for positions taken in current year	38	31	38
Increases for positions taken in prior years	51	10	13
Decreases for positions taken in prior years	(56)	(20)	(87)
Refunds from and settlements with taxing authorities	64
Payments to and settlements with taxing authorities		4	(13)
Increases/(decreases) for interest and penalties		6	(5)
Lapse of statutes of limitations	(43)		(3)
Unrecognized tax benefits at December 31	$ 179	$ 125	$ 94

Income Taxes (Unrecognized Tax

Income Taxes (Unrecognized Tax Benefits That Would/Not Reduce The Effective Tax Rate) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unrecognized Tax Benefits That Would Impact Effective Tax Rate [Abstract]
Unrecognized tax benefits that would reduce the effective tax rate	$ 83	$ 31	$ 31
Unrecognized tax benefits that would not reduce the effective tax rate	96	94	63
Total unrecognized tax benefits	$ 179	$ 125	$ 94	$ 151

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 7,278	$ 1,194	$ 1,168	$ 1,072	$ 1,144	$ 1,131	$ 979	$ 979	$ 10,712	$ 4,233	$ 4,772
Weighted-Average Number Of Shares Outstanding
Basic									798.4	832.4	866.2
Dilutive effect of stock options									1.8	1.5	1.5
Dilutive effect of retention shares and units									1.5	1.5	1.7
Diluted									801.7	835.4	869.4
Earnings per share – basic	$ 9.29	$ 1.50	$ 1.45	$ 1.32	$ 1.40	$ 1.36	$ 1.17	$ 1.16	$ 13.42	$ 5.09	$ 5.51
Earnings per share – diluted	$ 9.25	$ 1.50	$ 1.45	$ 1.32	$ 1.39	$ 1.36	$ 1.17	$ 1.16	$ 13.36	$ 5.07	$ 5.49
Stock options excluded as their inclusion would be anti-dilutive									1.6	2	1.1

Accumulated Other Comprehensi85

Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at January 1		$ (1,272)	$ (1,195)
Other comprehensive income/(loss) before reclassifications		30	(51)
Amounts reclassified from accumulated other comprehensive income/(loss)	[1]	101	(26)
Net year-to-date other comprehensive income/(loss), net of taxes	[2]	131	(77)	$ 15
Balance at December 31		(1,141)	(1,272)	(1,195)
Deferred taxes activity other comprehensive income/(loss)		(61)	49	(8)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at January 1		(1,132)	(1,103)
Other comprehensive income/(loss) before reclassifications		2	(3)
Amounts reclassified from accumulated other comprehensive income/(loss)	[1]	101	(26)
Net year-to-date other comprehensive income/(loss), net of taxes		103	(29)
Balance at December 31		(1,029)	(1,132)	(1,103)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at January 1		(140)	(92)
Other comprehensive income/(loss) before reclassifications		28	(48)
Amounts reclassified from accumulated other comprehensive income/(loss)	[1]
Net year-to-date other comprehensive income/(loss), net of taxes		28	(48)
Balance at December 31		$ (112)	$ (140)	$ (92)
[1]	The accumulated other comprehensive income/(loss) reclassification components are 1) prior service cost/(benefit) and 2) net actuarial loss which are both included in the computation of net periodic pension cost. See Note 6 Retirement Plans for additional details.
[2]	Net of deferred taxes of $(61) million, $49 million, $(8) million, and during 2017, 2016, and 2015, respectively.

Accounts Receivable (Details)

Accounts Receivable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Receivable Details [Abstract]
Allowance for doubtful accounts	$ 3	$ 5
Allowance for doubtful accounts - receivables not expected to be collected in one year	17	17
Receivables Securitization Facility [Abstract]
Total capacity to transfer undivided interests to investors under the receivables securitization facility	$ 650
Receivables securitization facility maturity date	2019-07
Receivables securitization facility duration	3 years
Value of the outstanding undivided interest held by investors under the receivables securitization facility	$ 500	0
Accounts receivable supporting the undivided interest held by investors	1,100	1,000
Cost of the receivables securitization facility - interest expense	$ 6	$ 7	$ 5

Properties (Details)

Properties (Details) $ in Millions		12 Months Ended
		Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Property, Plant and Equipment [Line Items]
Cost		$ 70,813	$ 69,058
Accumulated depreciation		19,208	18,669
Net book value		$ 51,605	50,389
Depreciable asset classes description		We currently have more than 60 depreciable asset classes, and we may increase or decrease the number of asset classes due to changes in technology, asset strategies, or other factors.
Total repairs and maintenance expense		$ 2,500	2,300	$ 2,500
Land [Member]
Property, Plant and Equipment [Line Items]
Cost		5,258	5,220
Accumulated depreciation
Net book value		5,258	5,220
Road: Rail and Other Track Material [Member]
Property, Plant and Equipment [Line Items]
Cost		16,327	15,845
Accumulated depreciation		5,929	5,722
Net book value		$ 10,398	$ 10,123
Estimated useful life		43 years	40 years
Road: Ties [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 10,132	$ 9,812
Accumulated depreciation		2,881	2,736
Net book value		$ 7,251	$ 7,076
Estimated useful life		33 years	33 years
Road: Ballast [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 5,406	$ 5,242
Accumulated depreciation		1,509	1,430
Net book value		$ 3,897	$ 3,812
Estimated useful life		34 years	34 years
Road: Other Roadway [Member]
Property, Plant and Equipment [Line Items]
Cost	[1]	$ 18,972	$ 18,138
Accumulated depreciation	[1]	3,482	3,226
Net book value	[1]	$ 15,490	$ 14,912
Estimated useful life	[1]	47 years	47 years
Total Road [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 50,837	$ 49,037
Accumulated depreciation		13,801	13,114
Net book value		$ 37,036	35,923
Term of Depreciation Studies		6 years
Equipment: Locomotives [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 9,686	9,692
Accumulated depreciation		3,697	3,939
Net book value		$ 5,989	$ 5,753
Estimated useful life		19 years	20 years
Equipment: Freight Cars [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 2,255	$ 2,243
Accumulated depreciation		983	972
Net book value		$ 1,272	$ 1,271
Estimated useful life		24 years	24 years
Equipment: Work Equipment and Other [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 936	$ 905
Accumulated depreciation		267	232
Net book value		$ 669	$ 673
Estimated useful life		19 years	19 years
Total Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 12,877	$ 12,840
Accumulated depreciation		4,947	5,143
Net book value		$ 7,930	7,697
Term of Depreciation Studies		3 years
Technology and Other [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 1,105	974
Accumulated depreciation		460	412
Net book value		$ 645	$ 562
Estimated useful life		11 years	11 years
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Cost		$ 736	$ 987
Accumulated depreciation
Net book value		$ 736	$ 987
2018 Minimum [Member]
Property, Plant and Equipment [Line Items]
Number of depreciable asset classes | item		60
[1]	Other roadway includes grading, bridges and tunnels, signals, buildings, and other road assets.

Accounts Payable And Other Cu88

Accounts Payable And Other Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable And Other Current Liabilities [Abstract]
Accounts payable	$ 1,013	$ 955
Income and other taxes payable	547	472
Accrued wages and vacation	384	387
Interest payable	220	212
Accrued casualty costs	194	185
Equipment rents payable	110	101
Other	671	570
Total accounts payable and other current liabilities	$ 3,139	$ 2,882

Financial Instruments (Details)

Financial Instruments (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Short-term investments [Abstract]
Short-term investments	$ 90,000,000	$ 60,000,000
Transfers out of level 2	0
Fair Value of Debt Instruments [Abstract]
Fair value of total debt	18,200,000,000	15,900,000,000
Fair value of total debt in excess of carrying value	1,300,000,000	900,000,000
Fixed rate debt securities containing call provisions	155,000,000	$ 155,000,000
Time Deposits [Member] | Significant Other Observable Inputs (Level 2) [Member]
Short-term investments [Abstract]
Short-term investments	$ 90,000,000

Debt (Equipment Encumbrances) (

Debt (Equipment Encumbrances) (Narrative) (Details) - USD ($) $ in Billions	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 1997
Debt [Abstract]
Carrying value of equipment serving as collateral for capital leases and other types of equipment obligations	$ 2	$ 2.3
Value of Missouri Pacific Railroad company assets that secured mortgage bonds			$ 6

Debt (Credit Facilities) (Narra

Debt (Credit Facilities) (Narrative) (Details) - Revolving Credit Facility [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Facility expiration date	May 25, 2019
Credit facility term	5 years
Revolving credit facility available credit	$ 1,700,000,000
Revolving credit facility withdrawals	0
Allowable debt per debt-to-net-worth coverage ratio (as defined in the facility)	49,700,000,000
Outstanding debt (as defined by facility)	17,000,000,000
Cross-default provision (as defined by facility)	125,000,000
Commercial paper issued	0
Commercial paper repaid	0
Commercial paper outstanding	$ 0	$ 0

Debt (Dividend Restrictions) (N

Debt (Dividend Restrictions) (Narrative) (Details) - USD ($) $ in Billions	Dec. 31, 2017	Dec. 31, 2016
Debt [Abstract]
Retained earnings available for dividends	$ 16.4	$ 12.4

Debt (Shelf Registration And Si

Debt (Shelf Registration And Significant New Borrowings) (Narrative) (Details) - USD ($)	Dec. 31, 2017	Jul. 28, 2016
Debt [Abstract]
Board of Directors authorized debt issuance		$ 4,000,000,000
Board of Directors remaining debt issuance	$ 1,550,000,000

Debt (Receivables Securitizatio

Debt (Receivables Securitization Facility) (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt	$ 17,831
Receivables Securitization (Note 11) [Member]
Debt Instrument [Line Items]
Debt	$ 500	$ 0

Debt (Schedule Of Debt) (Detail

Debt (Schedule Of Debt) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt	$ 17,831
Unamortized discount and deferred issuance costs	(887)	$ (894)
Total debt	16,944	15,007
Less: current portion	(800)	(758)
Total long-term debt	16,144	14,249
Notes and debentures [Member]
Debt Instrument [Line Items]
Debt	$ 15,096	13,547
Debt due through	Sep. 15, 2067
Notes and debentures [Member] | 2018 Minimum [Member]
Debt Instrument [Line Items]
Stated percentage rate	1.80%
Notes and debentures [Member] | 2018 Maximum [Member]
Debt Instrument [Line Items]
Stated percentage rate	7.90%
Capitalized leases [Member]
Debt Instrument [Line Items]
Debt	$ 892	1,105
Debt due through	Dec. 10, 2028
Capitalized leases [Member] | 2018 Minimum [Member]
Debt Instrument [Line Items]
Stated percentage rate	3.10%
Capitalized leases [Member] | 2018 Maximum [Member]
Debt Instrument [Line Items]
Stated percentage rate	8.40%
Equipment obligations [Member]
Debt Instrument [Line Items]
Debt	$ 1,018	1,069
Debt due through	Jan. 2, 2031
Equipment obligations [Member] | 2018 Minimum [Member]
Debt Instrument [Line Items]
Stated percentage rate	2.60%
Equipment obligations [Member] | 2018 Maximum [Member]
Debt Instrument [Line Items]
Stated percentage rate	6.70%
Term loans - floating rate [Member]
Debt Instrument [Line Items]
Debt	$ 250	100
Debt due through	Oct. 31, 2018
Mortgage bonds [Member]
Debt Instrument [Line Items]
Debt	$ 57	57
Stated percentage rate	4.80%
Debt due through	Jan. 1, 2030
Medium-term notes [Member]
Debt Instrument [Line Items]
Debt	$ 18	23
Debt due through	Apr. 15, 2020
Medium-term notes [Member] | 2018 Minimum [Member]
Debt Instrument [Line Items]
Stated percentage rate	9.30%
Medium-term notes [Member] | 2018 Maximum [Member]
Debt Instrument [Line Items]
Stated percentage rate	10.00%
Receivables Securitization (Note 11) [Member]
Debt Instrument [Line Items]
Debt	$ 500	$ 0

Debt (Aggregate Debt Maturities

Debt (Aggregate Debt Maturities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Aggregate Debt Maturities Excluding Market Value Adjustments [Abstract]
Debt maturities - 2018	$ 806
Debt maturities - 2019	1,125
Debt maturities - 2020	1,021
Debt maturities - 2021	677
Debt maturities - 2022	917
Debt maturities - thereafter	13,285
Total principal	17,831
Unamortized discount and deferred issuance costs	(887)	$ (894)
Total debt	$ 16,944	$ 15,007

Debt (Unsecured Fixed Rate Debt

Debt (Unsecured Fixed Rate Debt Securities Issued Under Current Shelf Registration) (Details) - Unsecured Debt [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Sep. 19, 2017	Apr. 05, 2017
3.000% Notes Due 2027 [Member]
Debt Instrument [Line Items]
Issuance date	Apr. 5, 2017
Note amount			$ 500,000,000
Interest rate on note			3.00%
Maturity date on new borrowing	Apr. 15, 2027
4.000% Notes Due 2047 [Member]
Debt Instrument [Line Items]
Issuance date	Apr. 5, 2017
Note amount			$ 500,000,000
Interest rate on note			4.00%
Maturity date on new borrowing	Apr. 15, 2047
3.600% Notes Due 2037 [Member]
Debt Instrument [Line Items]
Issuance date	Sep. 19, 2017
Note amount		$ 500,000,000
Interest rate on note		3.60%
Maturity date on new borrowing	Sep. 15, 2037
4.100% Notes Due 2067 [Member]
Debt Instrument [Line Items]
Issuance date	Sep. 19, 2017
Note amount		$ 500,000,000
Interest rate on note		4.10%
Maturity date on new borrowing	Sep. 15, 2067

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Millions	Dec. 31, 2017USD ($)
Future minimum lease payments	$ 2,649
Variable Interest Entity (VIEs) [Member]
Future minimum lease payments	$ 1,900

Leases (Narrative) (Details)

Leases (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Future Minimum Lease Payments For Capital Leases [Abstract]
Properties held under capital leases	$ 1,635	$ 1,997
Properties held under capital leases - accumulated depreciation	$ 953	1,121
Lease payments related to locomotives	97.00%
Future Minimum Lease Payments For Operating Leases [Abstract]
Rent expense for operating leases with terms exceeding one month	$ 480	$ 535	$ 590

Leases (Future Minimum Lease Pa

Leases (Future Minimum Lease Payments For Operating And Capital Leases) (Details) $ in Millions	Dec. 31, 2017USD ($)
Future Minimum Lease Payments For Capital Leases [Abstract]
Minimum capital lease payments - 2018	$ 173
Minimum capital lease payments - 2019	156
Minimum capital lease payments - 2020	164
Minimum capital lease payments - 2021	168
Minimum capital lease payments - 2022	147
Minimum capital lease payments - later years	271
Total minimum capital lease payments	1,079
Capital lease payments - amount representing interest	(187)
Capital lease payments - present value of minimum lease payments	892
Future Minimum Lease Payments For Operating Leases [Abstract]
Minimum operating lease payments - 2018	398
Minimum operating lease payments - 2019	359
Minimum operating lease payments - 2020	297
Minimum operating lease payments - 2021	259
Minimum operating lease payments - 2022	221
Minimum operating lease payments - later years	1,115
Total minimum operating lease payments	$ 2,649

Commitments And Contingencie101

Commitments And Contingencies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)site	Dec. 31, 2016USD ($)
Commitments and Contingencies [Line Items]
Sites identified which we are or may be liable for remediation costs | site	315
Sites subject of actions taken by the U.S. government | site	33
Sites on the Superfund National Priorities List | site	21
Personal Injury [Member]
Commitments and Contingencies [Line Items]
Percent of liability recorded related to asserted claims	95.00%
Percent of liability recorded related to unasserted claims	5.00%
Personal Injury [Member] | 2018 Minimum [Member]
Commitments and Contingencies [Line Items]
Reasonably possible outcome of related claims	$ 285
Personal Injury [Member] | 2018 Maximum [Member]
Commitments and Contingencies [Line Items]
Reasonably possible outcome of related claims	$ 310
Asbestos [Member]
Commitments and Contingencies [Line Items]
Percent of liability recorded related to asserted claims	16.00%
Percent of liability recorded related to unasserted claims	84.00%
Asbestos [Member] | 2018 Minimum [Member]
Commitments and Contingencies [Line Items]
Reasonably possible outcome of related claims	$ 99
Asbestos [Member] | 2018 Maximum [Member]
Commitments and Contingencies [Line Items]
Reasonably possible outcome of related claims	105
Guarantees [Member]
Commitments and Contingencies [Line Items]
Maximum potential amount of guarantee payments	33	$ 43
Recorded liability for fair value of guarantees	$ 0	$ 0
Expiration year of final guarantee	The final guarantee expires in 2022.

Commitments And Contingencie102

Commitments And Contingencies (Commitments And Contingencies Activity) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies [Line Items]
Current portion, ending balance at December 31	$ 194	$ 185
Environmental [Abstract]
Beginning balance.	212	190	$ 182
Accruals	45	84	61
Payments	(61)	(62)	(53)
Ending balance at December 31	196	212	190
Current portion, ending balance at December 31	57	55	52
Personal Injury [Member]
Commitments and Contingencies [Line Items]
Beginning balance	290	318	335
Current year accruals	77	75	89
Changes in estimates for prior years	(7)	(29)	(3)
Payments	(75)	(74)	(103)
Ending balance at December 31	285	290	318
Current portion, ending balance at December 31	66	62	63
Asbestos [Member]
Commitments and Contingencies [Line Items]
Beginning balance	111	120	126
Current year accruals	(1)	12
Payments	(11)	(21)	(6)
Ending balance at December 31	99	111	120
Current portion, ending balance at December 31	$ 9	$ 8	$ 6

Share Repurchase Program (Detai

Share Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended			132 Months Ended
	Feb. 08, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Jan. 01, 2017
Share Repurchase Program [Line Items]
BOD authorized														120,000,000
Stock repurchase program expiration date										Dec. 31, 2020
Aggregate cost										$ 4,013	$ 3,105	$ 3,465	$ 23,200
Shares repurchased		9,231,510	11,801,755	7,788,283	7,531,300	9,624,667	9,088,613	7,026,100	9,315,807	36,352,848	35,055,187
Average purchase price		$ 119.37	$ 106.69	$ 109.10	$ 106.55	$ 97.60	$ 93.63	$ 85.66	$ 76.49	$ 110.40	$ 88.57
Subsequent Event [Member]
Share Repurchase Program [Line Items]
Aggregate cost	$ 349
Shares repurchased	2,600,000

Related Parties (Details)

Related Parties (Details) - TTX Company [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Equity method investment, ownership percentage	36.79%
Equity method investments	$ 1,200	$ 877
Related party transaction, expenses from transactions with related party	388	368	$ 376
Accounts payable, related parties, current	$ 69	$ 61

Selected Quarterly Data (Una105

Selected Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Selected Quarterly Data (Unaudited) [Abstract]
Operating revenues	$ 5,450	$ 5,408	$ 5,250	$ 5,132	$ 5,168	$ 5,174	$ 4,770	$ 4,829	$ 21,240	$ 19,941	$ 21,813
Operating income	2,251	2,012	2,005	1,793	1,965	1,960	1,660	1,687	8,061	7,272	8,052
Net income	$ 7,278	$ 1,194	$ 1,168	$ 1,072	$ 1,144	$ 1,131	$ 979	$ 979	$ 10,712	$ 4,233	$ 4,772
Net income per share:
Earnings per share – basic	$ 9.29	$ 1.50	$ 1.45	$ 1.32	$ 1.40	$ 1.36	$ 1.17	$ 1.16	$ 13.42	$ 5.09	$ 5.51
Earnings per share – diluted	$ 9.25	$ 1.50	$ 1.45	$ 1.32	$ 1.39	$ 1.36	$ 1.17	$ 1.16	$ 13.36	$ 5.07	$ 5.49

Schedule Of Valuation And Qu106

Schedule Of Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Presented in Consolidated Statements of Financial Position [Abstract]
Allowance for doubtful accounts - current	$ 3	$ 5
Allowance for doubtful accounts - long-term	17	17
Accrued casualty costs, current	194	185
Allowance For Doubtful Accounts [Member]
Schedule Of Valuation And Qualifying Accounts [Line Items]
Balance, beginning of period	22	16	$ 21
Charges/(reduction) to expense	1	23	1
Net recoveries/(write-offs), cash payments and other reductions	(3)	(17)	(6)
Balance, end of period	20	22	16
Presented in Consolidated Statements of Financial Position [Abstract]
Allowance for doubtful accounts - current	3	5	5
Allowance for doubtful accounts - long-term	17	17	11
Balance, end of period	20	22	16
Accrued Casualty Costs [Member]
Schedule Of Valuation And Qualifying Accounts [Line Items]
Balance, beginning of period	716	736	757
Charges/(reduction) to expense	167	202	227
Net recoveries/(write-offs), cash payments and other reductions	(199)	(222)	(248)
Balance, end of period	684	716	736
Presented in Consolidated Statements of Financial Position [Abstract]
Accrued casualty costs, current	194	185	181
Accrued casualty costs, long-term	490	531	555
Balance, end of period	$ 684	$ 716	$ 736