CSX (CSX) 10-K 7 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	Jan. 31, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	CSX CORP
Entity Central Index Key	277,948
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 47
Entity Common Stock, Shares Outstanding		887,236,080
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017

CONSOLIDATED INCOME STATEMENTS

CONSOLIDATED INCOME STATEMENTS - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Income Statement [Abstract]
Revenue	$ 11,408	$ 11,069	$ 11,811
Expense
Labor and Fringe	2,914	3,159	3,290
Materials, Supplies and Other	2,113	2,092	2,356
Depreciation	1,315	1,301	1,208
Fuel	864	713	957
Equipment and Other Rents	429	465	456
Restructuring Charges (Note 1)	325	0	0
Equity Earnings of Affiliates	(219)	(50)	(40)
Total Expense	7,741	7,680	8,227
Operating Income	3,667	3,389	3,584
Interest Expense	(546)	(579)	(544)
Debt Repurchase Expense	0	(115)	0
Other Income (Expense) - Net (Note 10)	21	46	98
Earnings Before Income Taxes	3,142	2,741	3,138
Income Tax Benefit (Expense) (Note 11)	2,329	(1,027)	(1,170)
Net Earnings	$ 5,471	$ 1,714	$ 1,968
Net Earnings Per Share
Basic (in dollars per share)	$ 6.01	$ 1.81	$ 2
Assuming Dilution (in dollars per share)	$ 5.99	$ 1.81	$ 2
Average Common Shares Outstanding
Basic (shares)	911	947	983
Assuming Dilution (shares)	914	948	984
Cash Dividends Paid Per Common Share	$ 0.78	$ 0.72	$ 0.70

CONSOLIDATED COMPREHENSIVE INCO

CONSOLIDATED COMPREHENSIVE INCOME STATEMENTS - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Net Earnings	$ 4,140	$ 459	$ 510	$ 362	$ 458	$ 455	$ 445	$ 356	$ 5,471	$ 1,714	$ 1,968
Other Comprehensive Income (Loss), Net of Tax									154	25	1
Comprehensive Earnings									5,625	1,739	1,969
Pension and Other Post-Employment Benefits
Other Comprehensive Income (Loss), Net of Tax									140	21	10
Other
Other Comprehensive Income (Loss), Net of Tax									$ 14	$ 4	$ (9)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015	Dec. 26, 2014
Current Assets:
Cash and Cash Equivalents (Note 1)	$ 401	$ 603	$ 628	$ 669
Short-term Investments	18	417
Accounts Receivable - Net (Note 1)	970	938
Materials and Supplies	372	407
Other Current Assets	154	122
Total Current Assets	1,915	2,487
Properties	44,324	43,227
Accumulated Depreciation	(12,560)	(12,077)
Properties - Net	31,764	31,150
Other Long-term Assets	374	318
Total Assets	35,739	35,414
Current Liabilities:
Accounts Payable	847	806
Labor and Fringe Benefits Payable	602	545
Casualty, Environmental and Other Reserves	108	115
Current Maturities of Long-term Debt	19	331
Income and Other Taxes Payable	157	129
Other Current Liabilities	161	114
Total Current Liabilities	1,894	2,040
Noncurrent Liabilities
Casualty, Environmental and Other Reserves	266	259
Long-term Debt (Note 9)	11,790	10,962
Deferred Income Taxes - Net (Note 11)	6,418	9,596
Other Long-term Liabilities	650	863
Total Liabilities	21,018	23,720
Shareholders' Equity:
Common Stock, $1 Par Value (Note 3)	890	928
Other Capital	217	138
Retained Earnings (Note 1)	14,084	11,253
Accumulated Other Comprehensive Loss (Note 14)	(486)	(640)
Noncontrolling Minority Interest	16	15
Total Shareholders' Equity	14,721	11,694	$ 11,668	$ 11,176
Total Liabilities and Shareholders' Equity	35,739	35,414
Investments in Conrail
Current Assets:
Investment in Affiliates, Subsidiaries and Other	907	840
Affiliates and Other Companies
Current Assets:
Investment in Affiliates, Subsidiaries and Other	$ 779	$ 619

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 30, 2016
Statement of Financial Position [Abstract]
Common stock par value (in dollars per share)	$ 1	$ 1

CONSOLIDATED CASH FLOW STATEMEN

CONSOLIDATED CASH FLOW STATEMENTS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
OPERATING ACTIVITIES
Net Earnings	$ 5,471	$ 1,714	$ 1,968
Adjustments to Reconcile Net Earnings to Net Cash
Depreciation	1,315	1,301	1,208
Restructuring Charge (Note 1)	325	0	0
Cash Payments for Restructuring Charge	(187)	0	0
Deferred Income Taxes	(3,233)	405	456
Earnings of equity-method investments	(219)	(50)	(40)
Contributions to Qualified Pension Plans (Note 8)	0	(250)	0
Gain on Property Dispositions	(18)	(128)	(90)
Other Operating Activities	(17)	(20)	62
Changes in Operating Assets and Liabilities:
Accounts Receivable	(70)	84	149
Other Current Assets	1	(113)	(84)
Accounts Payable	41	40	(79)
Income and Other Taxes Payable	20	23	(62)
Other Current Liabilities	43	35	(118)
Net Cash Provided by Operating Activities	3,472	3,041	3,370
INVESTING ACTIVITIES
Property Additions	(2,040)	(2,398)	(2,562)
Purchase of Short-term Investments	(782)	(929)	(1,739)
Proceeds from Sales of Short-term Investments	1,193	1,325	1,225
Proceeds from Property Dispositions	97	195	147
Other Investing Activities	37	9	37
Net Cash Used in Investing Activities	(1,495)	(1,798)	(2,892)
FINANCING ACTIVITIES
Long-term Debt Issued (Note 9)	850	2,200	1,200
Long-term Debt Repaid (Note 9)	(333)	(1,419)	(229)
Dividends Paid	(708)	(680)	(686)
Shares Repurchased	(1,970)	(1,056)	(804)
Other Financing Activities	(18)	(313)	0
Net Cash Used in Financing Activities	(2,179)	(1,268)	(519)
Net Decrease in Cash and Cash Equivalents	(202)	(25)	(41)
CASH AND CASH EQUIVALENTS
Cash and Cash Equivalents at Beginning of Period	603	628	669
Cash and Cash Equivalents at End of Period	401	603	628
SUPPLEMENTAL CASH FLOW INFORMATION
Interest Paid - Net of Amounts Capitalized	555	606	566
Income Taxes Paid	911	580	768
Seller Financed Assets	$ 0	$ 0	$ 307

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Millions	Total	Common Shares Outstanding	Common Stock and Other Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)		Non- controlling Interest
Common Shares Outstanding, beginning balance (in shares) at Dec. 26, 2014		991,591
Shareholders' Equity, beginning balance at Dec. 26, 2014	$ 11,176		$ 1,084	$ 10,734	$ (666)	[1]	$ 24
Comprehensive Earnings:
Net Earnings	1,968			1,968
Other Comprehensive Income (Note 14)	1				1	[1]
Comprehensive Earnings	1,969
Common stock dividends	$ (686)			(686)
Share Repurchases (in shares)	(26,000)	(26,359)
Share Repurchases	$ (804)		(26)	(778)
Bond Conversions (in shares)		13
Bond Conversions	0
Other (in shares)		269
Other	13		21				(8)
Common Shares Outstanding, ending balance (in shares) at Dec. 25, 2015		965,514
Shareholders' Equity, ending balance at Dec. 25, 2015	11,668		1,079	11,238	(665)	[1]	16
Comprehensive Earnings:
Accumulated other comprehensive loss, tax	7				347
Net Earnings	1,714			1,714
Other Comprehensive Income (Note 14)	25				25	[1]
Comprehensive Earnings	1,739
Common stock dividends	$ (680)			(680)
Share Repurchases (in shares)	(38,000)	(38,379)
Share Repurchases	$ (1,056)		(38)	(1,018)
Bond Conversions (in shares)		94
Bond Conversions	1		1
Other (in shares)		951
Other	22		24	(1)			(1)
Common Shares Outstanding, ending balance (in shares) at Dec. 30, 2016		928,180
Shareholders' Equity, ending balance at Dec. 30, 2016	11,694		1,066	11,253	(640)	[1]	15
Comprehensive Earnings:
Accumulated other comprehensive loss, tax	13				335
Net Earnings	5,471			5,471
Other Comprehensive Income (Note 14)	154				154	[1]
Comprehensive Earnings	5,625
Common stock dividends	$ (708)			(708)
Share Repurchases (in shares)	(39,000)	(38,785)
Share Repurchases	$ (1,970)		(39)	(1,931)
Other (in shares)		456
Other	80		80	(1)			1
Common Shares Outstanding, ending balance (in shares) at Dec. 31, 2017		889,851
Shareholders' Equity, ending balance at Dec. 31, 2017	14,721		$ 1,107	$ 14,084	(486)	[1]	$ 16
Comprehensive Earnings:
Accumulated other comprehensive loss, tax	$ 65				$ 162
[1]	Accumulated Other Comprehensive Loss year-end balances shown above are net of tax. The associated taxes were $162 million, $335 million and $347 million for 2017, 2016 and 2015, respectively. For additional information see Note 14, Other Comprehensive Income.

CONSOLIDATED STATEMENTS OF CHA8

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Statement of Stockholders' Equity [Abstract]
Cash Dividends Paid Per Common Share	$ 0.78	$ 0.72	$ 0.70

Nature of Operations and Signif

Nature of Operations and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations and Significant Accounting Policies	Nature of Operations and Significant Accounting Policies Business CSX Corporation (“CSX”), together with its subsidiaries (the “Company”), based in Jacksonville, Florida, is one of the nation's leading transportation companies. The Company provides rail-based transportation services including traditional rail service, the transport of intermodal containers and trailers, as well as other transportation services such as rail-to-truck transfers and bulk commodity operations. The Company’s number of employees was approximately 24,000 as of December 2017 , which includes approximately 20,000 union employees. Most of the Company’s employees provide or support transportation services. CSX Transportation, Inc. CSX’s principal operating subsidiary, CSX Transportation, Inc. (“CSXT”), provides an important link to the transportation supply chain through its approximately 21,000 route mile rail network, which serves major population centers in 23 states east of the Mississippi River, the District of Columbia and the Canadian provinces of Ontario and Quebec. It has access to over 70 ocean, river and lake port terminals along the Atlantic and Gulf Coasts, the Mississippi River, the Great Lakes and the St. Lawrence Seaway. The Company’s intermodal business links customers to railroads via trucks and terminals. CSXT also serves thousands of production and distribution facilities through track connections to approximately 230 short-line and regional railroads. CSXT is now responsible for the Company's real estate sales, leasing, acquisition and management and development activities after a merger with CSX Real Property, Inc., a former wholly-owned CSX subsidiary, on July 1, 2017. In addition, as substantially all real estate sales, leasing, acquisition and management and development activities are focused on supporting railroad operations, all results of these activities are included in operating income beginning in 2017. Previously, the results of these activities were classified as operating or non-operating based on the nature of the activity and were not material for any periods presented. NOTE 1. Nature of Operations and Significant Accounting Policies, continued Lines of Business During 2017 , the Company's services generated $11.4 billion of revenue and served three primary lines of business: merchandise, coal and intermodal. • The merchandise business shipped 2.7 million carloads and generated 62 percent of revenue and 42 percent of volume in 2017 . The Company’s merchandise business is comprised of shipments in the following diverse markets: chemicals, automotive, agricultural and food products, minerals, fertilizers, forest products, and metals and equipment. • The coal business shipped about 855 thousand carloads and accounted for 18 percent of revenue and 13 percent of volume in 2017 . The Company transports domestic coal, coke and iron ore to electricity-generating power plants, steel manufacturers and industrial plants as well as export coal to deep-water port facilities. Roughly one-third of export coal and the majority of the domestic coal that the Company transports is used for generating electricity. • The intermodal business accounted for 16 percent of revenue and 44 percent of volume in 2017 . The intermodal business combines the superior economics of rail transportation with the short-haul flexibility of trucks and offers a cost advantage over long-haul trucking. Through a network of more than 40 terminals, the intermodal business serves all major markets east of the Mississippi River and transports mainly manufactured consumer goods in containers, providing customers with truck-like service for longer shipments. Other revenue accounted for 4 percent of the Company’s total revenue in 2017 . This revenue category includes revenue from regional subsidiary railroads, demurrage, revenue for customer volume commitments not met, switching, other incidental charges and adjustments to revenue reserves. Revenue from regional railroads includes shipments by railroads that the Company does not directly operate. Demurrage represents charges assessed when freight cars or other equipment are held beyond a specified period of time. Switching revenue is primarily generated when CSXT switches cars for a customer or another railroad. Other Entities In addition to CSXT, the Company’s subsidiaries include CSX Intermodal Terminals, Inc. (“CSX Intermodal Terminals”), Total Distribution Services, Inc. (“TDSI”), Transflo Terminal Services, Inc. (“Transflo”), CSX Technology, Inc. (“CSX Technology”) and other subsidiaries. CSX Intermodal Terminals owns and operates a system of intermodal terminals, predominantly in the eastern United States and also performs drayage services (the pickup and delivery of intermodal shipments) for certain customers and trucking dispatch operations. TDSI serves the automotive industry with distribution centers and storage locations. Transflo connects non-rail served customers to the many benefits of rail by transferring products from rail to trucks. The biggest Transflo markets are chemicals and agriculture, which includes shipments of plastics and ethanol. CSX Technology and other subsidiaries provide support services for the Company. Basis of Presentation In the opinion of management, the accompanying consolidated financial statements contain all normal, recurring adjustments necessary to fairly present the financial position of CSX and its subsidiaries at December 31, 2017 and December 30, 2016 , and the consolidated statements of income, comprehensive income, cash flows and changes in shareholders’ equity for fiscal years 2017 , 2016 and 2015 . In addition, management has evaluated and disclosed all material events occurring subsequent to the date of the financial statements up to the date this annual report is filed on Form 10-K. NOTE 1. Nature of Operations and Significant Accounting Policies, continued Fiscal Year Through the second quarter 2017, CSX followed a 52/53 week fiscal reporting calendar with the last day of each reporting period ending on a Friday. The 52/53 week calendar allowed for every quarter and year to be of equal duration, 13 weeks and 52 weeks, respectively. To maintain this calendar, every fifth or sixth year, an extra week was added to the fourth quarter and year, making the reporting periods 14 weeks and 53 weeks, respectively. In 2016, the fourth quarter and fiscal year included this extra week. On July 7, 2017, the Board of Directors of CSX approved a change in the fiscal reporting calendar from a 52/53 week year ending on the last Friday of December to a calendar year ending on December 31 each year, effective beginning with fiscal third quarter 2017. Related to the change in the fiscal calendar: • Fiscal year 2017 (December 31, 2016 through December 31, 2017) contained 366 days, and fiscal year 2016 (December 26, 2015 through December 30, 2016) contained 371 days • Fiscal first quarter 2017 (December 31, 2016 through March 31, 2017) contained 91 days, and fiscal first quarter 2016 (December 26, 2015 through March 25, 2016) contained 91 days • Fiscal second quarter 2017 (April 1, 2017 through June 30, 2017) contained 91 days, and fiscal second quarter 2016 (September 24, 2016 through December 30, 2016) contained 91 days • Fiscal third quarter 2017 (July 1, 2017 through September 30, 2017) contained 92 days, and fiscal third quarter 2016 (June 25, 2016 through September 23, 2016) contained 91 days • Fiscal fourth quarter 2017 (October 1, 2017 through December 31, 2017) contained 92 days, and fiscal fourth quarter 2016 (September 24, 2016 through December 30, 2016) contained 98 days This change did not materially impact comparability of the Company’s financial results for fiscal year 2016 and fiscal year 2017. Accordingly, the change to a calendar fiscal year was made on a prospective basis and operating results for prior periods have not been adjusted. The Company is not required to file a transition report because this change is not deemed a change in fiscal year for purposes of reporting subject to Rule 13a-10 or Rule 15d-10 of the Securities Exchange Act of 1934 as the new fiscal year commenced with the end of the prior fiscal year end and within seven days of the prior fiscal year end. Except as otherwise specified, references to full years indicate CSX’s fiscal years ended on December 31, 2017 and December 30, 2016. Principles of Consolidation The consolidated financial statements include results of operations of CSX and subsidiaries over which CSX has majority ownership or financial control. All significant intercompany accounts and transactions have been eliminated. Most investments in companies that were not majority-owned were carried at cost (if less than 20% owned and the Company has no significant influence) or were accounted for under the equity method (if the Company has significant influence but does not have control). These investments are reported within Investment in Conrail or Affiliates and Other Companies on the consolidated balance sheets. Cash and Cash Equivalents On a daily basis, cash in excess of current operating requirements is invested in various highly liquid investments having a typical maturity date of three months or less at the date of acquisition. These investments are carried at cost, which approximated market value, and are classified as cash equivalents. NOTE 1. Nature of Operations and Significant Accounting Policies, continued Investments Investments in instruments with original maturities greater than three months that will mature in less than one year are classified as short-term investments. Investments with original maturities of one year or greater are initially classified within other long-term assets, and the classification is re-evaluated at each balance sheet date. Allowance for Doubtful Accounts The Company maintains an allowance for doubtful accounts on uncollectible amounts related to freight receivables, government reimbursement receivables, claims for damages and other various receivables. The allowance is based upon the creditworthiness of customers, historical experience, the age of the receivable and current market and economic conditions. Uncollectible amounts are charged against the allowance account. Allowance for doubtful accounts of $26 million and $33 million is included in the consolidated balance sheets as of December 2017 and December 2016 , respectively. Materials and Supplies Materials and supplies in the consolidated balance sheets are carried at average costs and consist primarily of fuel and parts used in the repair and maintenance of CSXT’s freight car and locomotive fleets, equipment and track structure. Goodwill Goodwill represents purchase price in excess of fair value and is related to affiliates of CSXT, primarily P&L Transportation, Inc. Goodwill of $63 million is recorded in other long-term assets in the consolidated balance sheets as of December 2017 and December 2016 , respectively. Revenue and Expense Recognition The Company recognizes freight revenue using Free-On-Board Origin pursuant to the Revenue Recognition Topic in the Accounting Standards Codification ("ASC"). Accounting guidance in this topic provides for the allocation of revenue between reporting periods based on relative transit time in each reporting period. Expenses are recognized as incurred. The certain key estimates included in the recognition and measurement of revenue and related accounts receivable under the policies described above are as follows: • revenue associated with shipments in transit is recognized ratably over transit time and is based on average cycle times to move commodities and products from their origin to their final destination or interchange; • adjustments to revenue for billing corrections, billing discounts and bad debts or to accounts receivable for allowances for doubtful accounts; • adjustments to revenue for overcharge claims filed by customers, which are based on historical cash paid to customers for rate overcharges as a percentage of total billing; • incentive-based refunds to customers, which are primarily based on customers achieving certain volume thresholds, are recorded as a reduction to revenue on the basis of management’s best estimate of the projected liability (this estimate is based on historical activity, current volume levels and forecasted future volume). NOTE 1. Nature of Operations and Significant Accounting Policies, continued The Company regularly updates the estimates described above based on historical experience and current conditions. All other revenue, such as demurrage, switching and other incidental charges are recorded upon completion of the service. New Accounting Pronouncements In May 2017, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") Compensation - Stock Compensation: Scope of Modification Accounting, which provides clarity on what changes to share-based awards are considered substantive and require modification accounting to be applied. This update is required beginning with first quarter 2018 and should be applied prospectively to award modifications after the effective date. The Company early adopted this standard update in second quarter 2017 and will apply it prospectively to any award modifications after the adoption date. The Company does not regularly modify the terms and conditions of share-based awards and does not believe this standard update will have a material effect on its financial condition, results of operations or liquidity. In March 2017, the FASB issued ASU Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost , which requires that only the service cost component of net periodic benefit costs be recorded as compensation cost in the operating expense section of the income statement. All other components of net periodic benefit cost (interest cost, expected return on plan assets and amortization of net loss) will be presented in other income - net. This standard update is effective beginning with the first quarter 2018 and must be applied retrospectively. The Company does not believe this standard update will have a material effect on its financial condition, results of operations or liquidity. The Company currently records service costs and net benefit costs within labor and fringe expense. In 2017, pension and other post-retirement benefit charges and pension settlement charges totaling $85 million were included in the restructuring charge. Beginning in first quarter 2018, only the service cost will be recorded within labor and fringe expense, and the other components of net benefit costs will be recorded in other income. The retrospective impact of adoption will be an increase in operating income for the prior years presented as the other components were a net expense. The impact of adoption is projected to be a decrease in operating income for 2018. The retrospective impact of adoption is shown in the following table. Fiscal Years 2017 2016 2015 Increase in Operating Income $ 53 $ 24 $ 44 Decrease in Other Income (53 ) (24 ) (44 ) In March 2017, the FASB issued ASU Simplifying the Test for Goodwill Impairment, which eliminates step two, the calculation of the implied fair value of goodwill, from the goodwill impairment test. Impairment will be quantified in step one of the test as the amount by which the carrying amount exceeds the fair value. This standard update is effective beginning first quarter 2020 and must be applied prospectively. The Company does not believe this standard update will have a material effect on its financial condition, results of operations or liquidity. NOTE 1. Nature of Operations and Significant Accounting Policies, continued In May 2014, the FASB issued ASU Revenue from Contracts with Customers , which supersedes previous revenue recognition guidance. The new standard requires that a company recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration the company expects to receive in exchange for those goods or services. Companies will need to use more judgment and estimates than under the guidance currently in effect, including estimating the amount of variable revenue to recognize over each identified performance obligation. Additional disclosures will be required to help users of financial statements understand the nature, amount and timing of revenue and cash flows arising from contracts. CSX will adopt this standard update in first quarter 2018 using a modified retrospective method of adoption. The FASB has also issued several amendments to the revenue standard, including clarification on accounting for principal versus agent considerations (i.e., reporting gross versus net), licenses of intellectual property and identifying performance obligations. These amendments do not change the core principle of the standard, but provide clarity and implementation guidance. The Company is currently finalizing its review of the impact of adopting this new guidance and has developed a comprehensive implementation plan. In-depth reviews of commercial contracts have been completed and changes to processes and internal controls to meet the standard’s reporting and disclosure requirements have been identified and are being implemented. Adoption of this standard update will not materially impact the Company's financial condition, results of operations or liquidity. Freight revenue will continue to be recognized ratably over transit time. Additionally, the disaggregated revenue information required to be disclosed under this standard update is similar to the information currently included in the Results of Operations section of Item 2, “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” In February 2016, the FASB issued ASU, Leases , which will require lessees to recognize most leases on their balance sheets as a right-of-use asset with a corresponding lease liability, and lessors to recognize a net lease investment. Additional qualitative and quantitative disclosures will also be required. This standard update is effective for CSX beginning with the first quarter 2019 and will be adopted using a modified retrospective method. Changes to processes and internal controls to meet the standard’s reporting and disclosure requirements have been identified and are being implemented. Software has been implemented that will assist in the recognition of additional assets and liabilities to be included on the balance sheet related to leases currently classified as operating leases with durations greater than twelve months, with certain allowable exceptions. The Company continues to evaluate the expected impact of this standard update on disclosures, but does not anticipate any material changes to operating results or liquidity. NOTE 1. Nature of Operations and Significant Accounting Policies, continued Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires that management make estimates in reporting the amounts of certain assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of certain revenues and expenses during the reporting period. Actual results may differ from those estimates. Critical accounting estimates using management judgment are made for the following areas: • personal injury, environmental and legal reserves (see Note 5, Casualty, Environmental and Other Reserves ); • pension and post-retirement medical plan accounting (see Note 8, Employee Benefit Plans ); • depreciation policies for assets under the group-life method (see Note 6, Properties ); and • income taxes (see Note 11, Income Taxes ). Other Items Management Workforce Reduction Through an involuntary separation program with enhanced benefits to further its strategic objectives, CSX reduced its management workforce by approximately 950 employees during 2017. The Company has been focused on driving efficiencies through process improvement and responding to business mix shifts. These management reductions were designed to further streamline general and administrative and operating support functions to speed decision making and further control costs. In April 2017, the involuntary separation program was essentially completed. This program extends separation benefits for certain members of management that could result in additional charges through first quarter 2018. Accordingly, additional charges were incurred under the program throughout the year, including charges related to the separation of senior executives during fourth quarter 2017. The majority of separation benefits are being paid from general corporate funds while certain benefits are being paid through CSX’s qualified pension plans. Executive Retirements In first quarter 2017, the Company's former Chief Executive Officer, Michael J. Ward, and President, Clarence W. Gooden, announced their retirements, and the terms of their unvested equity awards were modified to permit prorated vesting through May 31, 2018. The lump-sum payments of their non-qualified pension benefits also resulted in a settlement charge in fourth quarter 2017. Reimbursement Arrangements In June 2017, the Company and the Company's former President and Chief Executive Officer, E. Hunter Harrison, executed a letter agreement providing for certain reimbursement arrangements. Pursuant to the letter agreement, the Company made a reimbursement payment to MR Argent Advisor LLC ("Mantle Ridge") of $55 million for funds previously paid to Mr. Harrison by Mantle Ridge. Further, the Company assumed Mantle Ridge’s obligation to pay Mr. Harrison, prior to March 15, 2018, a lump sum cash amount of $29 million in respect of other forfeited compensation from his previous employer, Canadian Pacific Railway Limited. This $29 million payment was made to his estate following his death in December 2017. The Company also assumed Mantle Ridge’s tax indemnification obligations to Mr. Harrison, which was intended to allow Mr. Harrison to remain in the same after-tax position as if he had not: (i) forfeited such compensation and benefits earned from CP; and (ii) received $55 million from Mantle Ridge. NOTE 1. Nature of Operations and Significant Accounting Policies, continued The ownership position of Mantle Ridge, a CSX shareholder, is detailed in the Company's Proxy Statement on Schedule 14A filed on April 20, 2017 and subsequent Form 4 filings with the SEC. The Vice-Chairman of CSX's Board of Directors, Paul C. Hilal, founded and controls Mantle Ridge and each of its related entities. At the Company's 2017 annual meeting of shareholders held on June 5, 2017, the Company's shareholders approved, on an advisory basis, with approximately 93 percent of the vote, the Company undertaking such reimbursement arrangements. Restructuring Charge The total restructuring charge includes costs related to the management workforce reduction, executive retirements, reimbursement arrangements, the proration of equity awards and other advisory costs related to the leadership transition. Future charges related to this restructuring are not expected to be material. Expenses related to the management workforce reduction and other costs are shown in the following table. 2017 (Dollars in millions) First Quarter Second Quarter Third Quarter Fourth Quarter Year-to-Date Severance $ 81 $ 10 $ — $ 7 $ 98 Pension and Other Post-Retirement Benefit Charges 63 7 — 3 73 Share-Based Compensation Remeasurement 5 3 — 7 15 Relocation 6 2 — — 8 Subtotal Management Workforce Reduction $ 155 $ 22 $ — $ 17 $ 194 Reimbursement Arrangements — 84 — — 84 Non-Cash Executive Equity Awards Proration 8 16 — — 24 Non-Cash Pension Settlement Charge — — — 12 12 Other Charges Including Fees Related to Shareholder Matters 10 — 1 — 11 Total Restructuring Charge $ 173 $ 122 $ 1 $ 29 $ 325 NOTE 1. Nature of Operations and Significant Accounting Policies, continued Charges and payments related to the management workforce reduction and other costs are shown in the following table. (Dollars in millions) 2017 Charges 2017 Payments Non-cash Items Liability 12/31/2017 Severance $ 98 $ (86 ) $ — $ 12 Pension, Other Post-Retirement Benefit Charges (a) 73 — (73 ) — Share-Based Compensation Remeasurement 15 — (15 ) — Relocation 8 (6 ) — 2 Subtotal Management Workforce Reduction $ 194 $ (92 ) $ (88 ) $ 14 Reimbursement Arrangements 84 (84 ) — — Non-Cash Executive Equity Awards Proration 24 — (24 ) — Non-Cash Pension Settlement Charge 12 — (12 ) — Other Charges Including Fees Related to Shareholder Matters 11 (11 ) — — Total Restructuring Charge $ 325 $ (187 ) $ (124 ) $ 14 (a) The majority of non-cash items are related to certain benefits paid through CSX's qualified pension plans. Separation Benefits Union agreements and facility closures in 2015, and management streamlining under workforce reduction plans announced in 2014 resulted in payment of separation benefits to employees of $51 million in 2015. These amounts are recognized in labor and fringe and materials, supplies and other on the consolidated statements of income. Separation benefits incurred in 2016 related to workforce reduction plans were not material.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table sets forth the computation of basic earnings per share and earnings per share, assuming dilution: Fiscal Years 2017 2016 2015 Numerator (Dollars in Millions) : Net Earnings $ 5,471 $ 1,714 $ 1,968 Dividend Equivalents on Restricted Stock (1 ) (1 ) (1 ) Net Earnings, Attributable to Common Shareholders $ 5,470 $ 1,713 $ 1,967 Denominator (Units in Millions) : Average Common Shares Outstanding 911 947 983 Other Potentially Dilutive Common Shares 3 1 1 Average Common Shares Outstanding, Assuming Dilution 914 948 984 Net Earnings Per Share, Basic $ 6.01 $ 1.81 $ 2.00 Net Earnings Per Share, Assuming Dilution $ 5.99 $ 1.81 $ 2.00 Basic earnings per share is based on the weighted-average number of shares of common stock outstanding. Earnings per share, assuming dilution, is based on the weighted-average number of shares of common stock equivalents outstanding adjusted for the effects of common stock that may be issued as a result of potentially dilutive instruments. CSX's potentially dilutive instruments are made up of equity awards, which include long-term incentive awards and employee stock options. The Earnings Per Share Topic in the ASC requires CSX to include additional shares in the computation of earnings per share, assuming dilution. The additional shares included in diluted earnings per share represent the number of shares that would be issued if all of the above potentially dilutive instruments were converted into CSX common stock. When calculating diluted earnings per share, CSX is required to include the potential shares that would be outstanding if all outstanding stock options were exercised. This number is different from outstanding stock options, which is included in Note 4, Stock Plans and Share-Based Compensation , because it is offset by shares CSX could repurchase using the proceeds from these hypothetical exercises to obtain the common stock equivalent. Approximately 7.6 million , 2.8 million and 2.5 million of total average outstanding stock options for 2017, 2016 and 2015, respectively, were excluded from the diluted earnings per share calculation because their effect was antidilutive. NOTE 2. Earnings Per Share, continued Share Repurchases Share repurchases under the $2 billion program announced in April 2015 were completed in April 2017. The Company subsequently announced a $1 billion share repurchase program in April 2017, with additional authority of $500 million added in July 2017. Repurchases under that program were completed on October 2, 2017, and the Company announced a new $1.5 billion share repurchase program on October 25, 2017. During 2017, 2016, and 2015, CSX repurchased the following shares: Fiscal Years 2017 2016 2015 Shares Repurchased (Units in Millions) 39 38 26 Cost of Shares (Dollars in Millions) $ 1,970 $ 1,056 $ 804 Management's assessment of market conditions and other factors guide the timing and volume of repurchases. Future share repurchases are expected to be funded by cash on hand, cash generated from operations and debt issuances. Shares are retired immediately upon repurchase. In accordance with the Equity Topic in the ASC, the Company elected to allocate the excess of repurchase price over par value and record in retained earnings. Generally, retained earnings is only impacted by net earnings and dividends.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity Common and preferred stock consists of the following: Common Stock, $1 Par Value December 2017 (Units in Millions) Common Shares Authorized 1,800 Common Shares Issued and Outstanding 890 Preferred Stock Preferred Shares Authorized 25 Preferred Shares Issued and Outstanding — Holders of common stock are entitled to one vote on all matters requiring a vote for each share held. Preferred stock is senior to common stock with respect to dividends and upon liquidation of CSX.

Stock Plans and Share-Based Com

Stock Plans and Share-Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Plans and Share-Based Compensation	Stock Plans and Share-Based Compensation Under CSX's share-based compensation plans, awards consist of performance units, restricted stock units, restricted stock awards and stock options for management and stock grants for directors. Awards granted under the various programs are determined and approved by the Compensation Committee of the Board of Directors or, in certain circumstances, by the Chief Executive Officer for awards to management employees other than senior executives. The Board of Directors approves awards granted to the Company’s non-management directors upon recommendation of the Governance Committee. Share-based compensation expense is measured using the fair value of the award on the grant date and is recognized on a straight-line basis over the service period of the respective award. Forfeitures are recognized as they occur. Total pre-tax expense associated with share-based compensation and its related income tax benefit is shown in the table below. The year over year increase in expense related to performance units and stock options is primarily due to modifications to the terms of awards (see Equity Award Modifications below) and higher expected award payouts. Fiscal Years (Dollars in Millions) 2017 2016 2015 Share-Based Compensation Expense Performance Units $ 49 $ 17 $ (1 ) Restricted Stock Units and Awards 15 11 11 Stock Options 22 7 — Stock Awards for Directors 3 2 2 Total Share-based Compensation Expense $ 89 $ 37 $ 12 Income Tax Benefit $ 34 $ 14 $ 4 Long-term Incentive Plans The CSX Long-term Incentive Plans (“LTIP”) were adopted under the 2010 CSX Stock and Incentive Award Plan. The objective of these plans is to motivate and reward certain employees for achieving and exceeding certain financial goals. Grants were made in performance units, with each unit being equivalent to one share of CSX common stock, and payouts will be made in CSX common stock. The payout range for participants will be between 0% and 200% of the target awards depending on Company performance against predetermined goals for each three -year cycle. In 2015, 2016 and 2017, target performance units were granted to certain employees under three separate LTIP plans covering three -year cycles: the 2015-2017 (“2015-2017 LTIP”), 2016-2018 (“2016-2018 LTIP”) and 2017-2019 (“2017-2019 LTIP”) plans (collectively, the “plans”). The key financial targets for the plans will be based on the achievement of goals related to both operating ratio and return on assets (tax-adjusted operating income divided by net property) excluding certain items as disclosed in the Company's financial statements. The three-year cumulative operating ratio and average return on assets over the performance period will each comprise 50% of the payout and are measured independently of the other. The plans state that payouts for certain executive officers are subject to downward adjustment by up to 30% based upon total shareholder return relative to specified comparable groups. NOTE 4. Stock Plans and Share-Based Compensation, continued Performance unit grant and vesting information is summarized as follows: Fiscal Years 2017 2016 2015 Weighted-average grant date fair value $ 49.50 $ 24.17 $ 35.45 Fair value of units vested in fiscal year ending (in millions) $ 26 $ 31 $ 34 The performance unit activity related to the outstanding long-term incentive plans and corresponding fair value is summarized as follows: Performance Units Outstanding Weighted-Average Fair Value at Grant Date Unvested at December 30, 2016 1,581 $ 30.00 Granted 644 49.50 Forfeited (530 ) 38.47 Vested (719 ) 35.94 Unvested at December 31, 2017 976 $ 33.90 As of December 2017, there was $24 million of total unrecognized compensation cost related to performance units that is expected to be recognized over a weighted-average period of approximately two years. Restricted Stock Grants Restricted stock grants consist of units and awards, each equivalent to one share of CSX stock. Restricted stock units are issued along with corresponding LTIP plans and vest three years after the date of grant. Separately, restricted stock awards generally vest over an employment period of up to five years. Participants receive cash dividend equivalents on the unvested shares during the restriction period. These awards are time-based and not based upon CSX’s attainment of operational targets. Restricted stock grant and vesting information is summarized as follows: Fiscal Years 2017 2016 2015 Weighted-average grant date fair value $ 48.35 $ 24.21 $ 35.94 Fair value of units and awards vested during fiscal year ended (in millions) $ 8 $ 14 $ 9 NOTE 4. Stock Plans and Share-Based Compensation, continued The restricted stock activity related to the outstanding long-term incentive plans and corresponding fair value is summarized as follows: Restricted Stock Units and Awards Outstanding Weighted-Average Fair Value at Grant Date Unvested at December 30, 2016 1,076 $ 28.19 Granted 328 48.35 Forfeited (297 ) 36.48 Vested (300 ) 28.09 Unvested at December 31, 2017 807 $ 33.37 As of December 2017, unrecognized compensation expense for these restricted stock units and awards was approximately $7 million , which will be expensed over a weighted-average remaining period of one year. Stock Options Stock options were granted in 2016 and 2017 along with the corresponding LTIP plans, and to certain members of management in 2015. Under this program, an employee receives an award that provides the opportunity in the future to purchase CSX shares at the closing market price of the stock on the date the award is granted (the strike price). The options become exercisable after a three -year vesting period and expire 10 years from the grant date if they are not exercised. The fair value of stock options granted was estimated as of the dates of grant using the Black-Scholes-Merton option model which uses the following assumptions: dividend yield, risk-free interest rate, annualized volatility and expected life. The annual dividend yield is based on the most recent quarterly CSX dividend payment annualized. The risk-free interest rate is based on U.S. Treasury yield curve in effect at the time of grant. The annualized volatility is based on historical volatility of daily CSX stock price returns over a 6.5 year look-back period ending on the grant date. The expected life is calculated using the safe harbor approach due to lack of historical data on CSX options, which is the midpoint between the vesting schedule ( three year cliff) and contractual term ( 10 years). On March 6, 2017, the Company granted 9 million stock options to former CEO E. Hunter Harrison at a fair value of $12.88 per option. These options were granted with a ten -year term and an exercise price equal to the closing market price of the underlying stock on the date of grant. Half of the options, or 4.5 million , were to vest on Mr. Harrison's service anniversary in equal annual installments over four years. The other half were to vest based on achievement of performance targets related to both operating ratio and earnings before interest, taxes, depreciation and amortization adjusted for certain items. Upon his death on December 16, 2017, all of Mr. Harrison's 9 million options were forfeited. NOTE 4. Stock Plans and Share-Based Compensation, continued Assumptions and inputs used to estimate fair value of stock options are summarized as follows: Fiscal Years 2017 2016 2015 Weighted-average grant date fair value $ 12.84 $ 4.68 $ 5.31 Stock options valuation assumptions: Annual dividend yield 1.5 % 3 % 3 % Risk-free interest rate 2.2 % 1 % 2 % Annualized volatility 27.1 % 27 % 28 % Expected life (in years) 6.3 6.5 6.5 Other pricing model inputs: Weighted-average grant-date market price of CSX stock (strike price) $ 49.63 $ 24.13 $ 24.99 The stock option activity is summarized as follows: Stock Options Outstanding Weighted-Average Exercise Price Outstanding at December 30, 2016 4,582 $ 24.57 Granted 10,462 49.63 Forfeited (10,860 ) 46.81 Exercised 22 25.18 Outstanding at December 31, 2017 4,163 $ 29.52 Exercisable at December 31, 2017 — — Unrecognized compensation expense related to stock options as of December 2017 was $10 million and is expected to be recognized over a weighted-average period of approximately one year. Equity Award Modifications The terms of performance units, restricted stock units and stock options granted as part of the Company’s long-term share-based compensation plans typically require participants to be employed through the final day of the respective performance or vesting periods as applicable, except in the case of death, disability or retirement. As part of an enhanced severance benefit under the management streamlining and realignment initiative discussed in Note 1, unvested performance units, restricted stock units and stock options for separated employees not eligible for retirement were permitted to vest on a pro-rata basis. Additionally, the terms of unvested equity awards for the former Chief Executive Officer, Michael J. Ward, and President, Clarence W. Gooden, were modified prior to their retirements on March 6, 2017 to permit prorated vesting through May 31, 2018. The terms were modified in exchange for each agreeing to serve in an advisory capacity upon request until May 31, 2017, and waiving various rights and claims, including the cancellation of their respective change of control agreements with the Company. NOTE 4. Stock Plans and Share-Based Compensation, continued The award modifications noted above impacted approximately 75 employees and resulted in an increase to share-based compensation expense for revaluation of the affected awards of $39 million for the year ended December 31, 2017. Stock Awards for Directors CSX’s non-management directors receive a base annual retainer of $100,000 to be paid quarterly in cash, unless the director chooses to defer the retainer in the form of cash or CSX common stock. Additionally, non-management directors receive an annual grant of common stock in the amount of approximately $150,000 , with the number of shares to be granted based on the average closing price of CSX stock in the months of November, December and January. In March 2017, the non-management Chairman received approximately $250,000 in the form of CSX stock valued on the third day after E. Hunter Harrison was named Chief Executive Officer and new Board members were announced.

Casualty, Environmental and Oth

Casualty, Environmental and Other Reserves	12 Months Ended
	Dec. 31, 2017
Casualty, Environmental and Other Reserves [Abstract]
Casualty, Environmental and Other Reserves	Casualty, Environmental and Other Reserves Activity related to casualty, environmental and other reserves is as follows: Casualty Environmental Other (Dollars in Millions) Reserves Reserves Reserves Total December 26, 2014 $ 265 $ 94 $ 59 $ 418 Charged to Expense 60 45 37 142 Payments (56 ) (57 ) (47 ) (160 ) December 25, 2015 269 82 49 400 Charged to Expense 52 46 30 128 Change in Estimate (a) (28 ) — — (28 ) Payments (64 ) (33 ) (29 ) (126 ) December 30, 2016 229 95 50 374 Charged to Expense 43 26 45 114 Payments (44 ) (31 ) (39 ) (114 ) December 31, 2017 $ 228 $ 90 $ 56 $ 374 (a) Changes in estimates are the result of continued safety improvements and a continuing decline in the severity of injuries. NOTE 5. Casualty, Environmental and Other Reserves, continued Personal injury and environmental reserves are considered critical accounting estimates due to the need for significant management judgment. Casualty, environmental and other reserves are provided for in the consolidated balance sheets as shown in the table below. December 2017 December 2016 (Dollars in Millions) Current Long-term Total Current Long-term Total Casualty: Personal Injury $ 43 $ 125 $ 168 $ 46 $ 124 $ 170 Occupational 6 54 60 7 52 59 Total Casualty $ 49 $ 179 $ 228 $ 53 $ 176 $ 229 Environmental 31 59 90 42 53 95 Other 28 28 56 20 30 50 Total $ 108 $ 266 $ 374 $ 115 $ 259 $ 374 These liabilities are accrued when reasonably estimable and probable in accordance with the Contingencies Topic in the ASC. Actual settlements and claims received could differ and final outcomes of these matters cannot be predicted with certainty. Considering the legal defenses currently available, the liabilities that have been recorded and other factors, it is the opinion of management that none of these items individually, when finally resolved, will have a material adverse effect on the Company's financial condition, results of operations or liquidity. Should a number of these items occur in the same period, however, their combined effect could be material in that particular period. Casualty Casualty reserves of $228 million and $229 million for 2017 and 2016 , respectively, represent accruals for personal injury, occupational disease and occupational injury claims. The Company's self-insured retention amount for these claims is $50 million per occurrence. Currently, no individual claim is expected to exceed the self-insured retention amount. In accordance with the Contingencies Topic in the ASC, to the extent the value of an individual claim exceeds the self-insured retention amount, the Company would present the liability on a gross basis with a corresponding receivable for insurance recoveries. These reserves fluctuate based upon the timing of payments as well as changes in estimate. Actual results may vary from estimates due to the number, type and severity of the injury, costs of medical treatments and uncertainties in litigation. Most of the Company's casualty claims relate to CSXT unless otherwise noted below. Defense and processing costs, which historically have been insignificant and are anticipated to be insignificant in the future, are not included in the recorded liabilities. NOTE 5. Casualty, Environmental and Other Reserves, continued Personal Injury Personal injury reserves represent liabilities for employee work-related and third-party injuries. Work-related injuries for CSXT employees are primarily subject to the Federal Employers' Liability Act ("FELA"). CSXT retains an independent actuary to assist management in assessing the value of personal injury claims. An analysis is performed by the actuary quarterly and is reviewed by management. The methodology used by the actuary includes a development factor to reflect growth or reduction in the value of these personal injury claims. It is based largely on CSXT's historical claims and settlement experience. During 2017 and 2015, there were no significant changes in estimate recorded to adjust casualty reserves. As a direct result of improvements in safety in recent years, the Company has experienced a downward trend in the severity of injuries, which has resulted in a decrease in the estimate of costs per incident. During 2016, the Company reduced casualty reserves, primarily personal injury reserves, by $28 million , resulting in an after-tax effect on earnings from continuing operations and net earnings of $18 million and an after-tax effect on earnings per share of $0.02 . The personal injury reserve reductions were included in materials, supplies and other on the consolidated income statements. Occupational Occupational reserves represent liabilities for occupational disease and injury claims. Occupational disease claims arise primarily from allegations of exposure to asbestos in the workplace. Occupational injury claims arise from allegations of exposure to certain other materials in the workplace, such as solvents, soaps, chemicals (collectively referred to as “irritants”) and diesel fuels (like exhaust fumes) or allegations of chronic physical injuries resulting from work conditions, such as repetitive stress injuries. Environmental Environmental reserves were $90 million and $95 million for 2017 and 2016 , respectively. The Company is a party to various proceedings related to environmental issues, including administrative and judicial proceedings involving private parties and regulatory agencies. The Company has been identified as a potentially responsible party at approximately 214 environmentally impaired sites. Many of these are, or may be, subject to remedial action under the federal Comprehensive Environmental Response, Compensation and Liability Act of 1980 ("CERCLA"), also known as the Superfund Law, or similar state statutes. Most of these proceedings arose from environmental conditions on properties used for ongoing or discontinued railroad operations. A number of these proceedings, however, are based on allegations that the Company, or its predecessors, sent hazardous substances to facilities owned or operated by others for treatment, recycling or disposal. In addition, some of the Company’s land holdings were leased to others for commercial or industrial uses that may have resulted in releases of hazardous substances or other regulated materials onto the property and could give rise to proceedings against the Company. In any such proceedings, the Company is subject to environmental clean-up and enforcement actions under the Superfund Law, as well as similar state laws that may impose joint and several liability for clean-up and enforcement costs on current and former owners and operators of a site without regard to fault or the legality of the original conduct. These costs could be substantial. NOTE 5. Casualty, Environmental and Other Reserves, continued In accordance with the Asset Retirement and Environmental Obligations Topic in the ASC, the Company reviews its role with respect to each site identified at least quarterly, giving consideration to a number of factors such as: • type of clean-up required; • nature of the Company’s alleged connection to the location (e.g., generator of waste sent to the site or owner or operator of the site); • extent of the Company’s alleged connection (e.g., volume of waste sent to the location and other relevant factors); and • number, connection and financial viability of other named and unnamed potentially responsible parties at the location. Based on the review process, the Company has recorded amounts to cover contingent anticipated future environmental remediation costs with respect to each site to the extent such costs are reasonably estimable and probable. The recorded liabilities for estimated future environmental costs are undiscounted. The liability includes future costs for remediation and restoration of sites as well as any significant ongoing monitoring costs, but excludes any anticipated insurance recoveries. Payments related to these liabilities are expected to be made over the next several years. Environmental remediation costs are included in materials, supplies and other on the consolidated income statements. Currently, the Company does not possess sufficient information to reasonably estimate the amounts of additional liabilities, if any, on some sites until completion of future environmental studies. In addition, conditions that are currently unknown could, at any given location, result in additional exposure, the amount and materiality of which cannot presently be reasonably estimated. Based upon information currently available, however, the Company believes its environmental reserves accurately reflect the estimated cost of remedial actions currently required. Other Other reserves of $56 million and $50 million for 2017 and 2016 , respectively, include liabilities for various claims, such as property, automobile and general liability. Also included in other reserves are longshoremen disability claims related to a previously owned international shipping business (these claims are in runoff) as well as claims for current port employees.

Properties

Properties	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Properties	Properties A detail of the Company’s net properties are as follows: (Dollars in Millions) Accumulated Net Book Annual Depreciation Estimated Useful Life Depreciation December 2017 Cost Depreciation Value Rate ( Avg. Years) Method (a) Road Rail and Other Track Material $ 7,694 $ (1,606 ) $ 6,088 2.5% 40 Group Life Ties 5,665 (1,446 ) 4,219 3.7% 27 Group Life Grading 2,662 (542 ) 2,120 1.4% 90 Group Life Ballast 2,994 (921 ) 2,073 2.7% 37 Group Life Bridges, Trestles, and Culverts 2,405 (356 ) 2,049 1.6% 70 Group Life Signals and Interlockers 2,759 (588 ) 2,171 4.0% 25 Group Life/ Straight Line Buildings 1,278 (464 ) 814 2.5% 40 Group Life Other 4,634 (1,867 ) 2,767 4.2% 24 Group Life Total Road 30,091 (7,790 ) 22,301 Equipment Locomotive 6,083 (2,490 ) 3,593 3.5% 29 Group Life Freight Cars 3,262 (998 ) 2,264 2.9% 35 Group Life Work Equipment and Other 2,261 (1,282 ) 979 7.4% 14 Group Life/ Straight Line Total Equipment 11,606 (4,770 ) 6,836 Land 1,849 — 1,849 N/A N/A N/A Construction In Progress 778 — 778 N/A N/A N/A Total Properties $ 44,324 $ (12,560 ) $ 31,764 (a) For depreciation method, certain asset categories contain intermodal terminals or technology-related assets, which are depreciated using the straight-line method. NOTE 6. Properties, continued (Dollars in Millions) Accumulated Net Book Annual Depreciation Estimated Useful Life Depreciation December 2016 Cost Depreciation Value Rate (Avg. Years) Method (a) Road Rail and Other Track Material $ 7,326 $ (1,493 ) $ 5,833 2.5% 40 Group Life Ties 5,368 (1,292 ) 4,076 3.7% 27 Group Life Grading 2,600 (514 ) 2,086 1.4% 90 Group Life Ballast 2,897 (860 ) 2,037 2.7% 37 Group Life Bridges, Trestles, and Culverts 2,306 (317 ) 1,989 1.6% 70 Group Life Signals and Interlockers 2,523 (496 ) 2,027 4.0% 25 Group Life/ Straight Line Buildings 1,238 (447 ) 791 2.5% 40 Group Life Other 4,566 (1,905 ) 2,661 4.2% 24 Group Life Total Road 28,824 (7,324 ) 21,500 Equipment Locomotive 6,110 (2,504 ) 3,606 3.5% 29 Group Life Freight Cars 3,386 (1,046 ) 2,340 2.9% 35 Group Life Work Equipment and Other 2,108 (1,190 ) 918 7.4% 14 Group Life/ Straight Line Total Equipment 11,604 (4,740 ) 6,864 Land 1,833 — 1,833 N/A N/A N/A Construction In Progress 913 — 913 N/A N/A N/A Other 53 (13 ) 40 N/A 32 Straight Line Total Properties $ 43,227 $ (12,077 ) $ 31,150 (a) For depreciation method, certain asset categories contain intermodal terminals or technology-related assets, which are depreciated using the straight-line method. NOTE 6. Properties, continued Capital Expenditures The Company’s capital investment includes purchased and self-constructed assets and property additions that substantially extend the service life or increase the utility of those assets. Indirect costs that can be specifically traced to capital projects are also capitalized. The Company is committed to maintaining and improving its existing infrastructure and expanding its network capacity for long-term growth. Rail operations are capital intensive and CSX accounts for these costs in accordance with GAAP and the Company’s capitalization policy. All properties are stated at historical cost less an allowance for accumulated depreciation. The Company’s largest category of capital investment is the replacement of track assets and the acquisition or construction of new assets that enable CSX to enhance its operations or provide new capacity offerings to its customers. These construction projects are primarily completed by CSXT employees. Costs for track asset replacement and capacity projects that are capitalized include: • labor costs, because many of the assets are self-constructed; • costs to purchase or construct new track or to prepare ground for the laying of track; • welding (rail, field and plant) which are processes used to connect segments of rail; • new ballast, which is gravel and crushed stone that holds track in line; • fuels and lubricants associated with tie, rail and surfacing work which is the process of raising track to a designated elevation over an extended distance; • cross, switch and bridge ties which are the braces that support the rails on a track; • gauging which is the process of standardizing the distance between rails; • handling costs associated with installing rail, ties or ballast; • usage charge of machinery and equipment utilized in construction or installation; and • other track materials. The primary cost in self-constructed track replacement work is labor. CSXT engineering employees directly charge their labor to the track replacement project (the capitalized depreciable property). These employees concurrently perform deconstruction and installation of track material. Because of this concurrent process, CSX must estimate the amount of labor that is related to deconstruction versus installation. Through analysis of CSXT’s track replacement process, CSX determined that approximately 20% of labor costs associated with track material installation is related to the deconstruction of old track and 80% is associated with the installation of new track. Capital investment related to locomotives and freight cars comprises the second largest category of the Company’s capital assets. This category includes purchase costs of locomotives and freight cars as well as certain equipment leases that are considered to be capital leases in accordance with the Leases Topic in the ASC. In addition, costs to modify or rebuild these assets are capitalized if the investment incurred extends the asset’s service life or improves utilization. Improvement projects must meet specified dollar thresholds to be capitalized and are reviewed by management to determine proper accounting treatment. Routine repairs and maintenance costs, for all asset categories, are expensed as incurred. NOTE 6. Properties, continued Depreciation Method The depreciable assets of the Company are depreciated using either the group-life or straight-line method of accounting, which are both acceptable depreciation methods in accordance with GAAP. The Company depreciates its railroad assets, including main-line track, locomotives and freight cars, using the group-life method. Assets depreciated under the group-life method comprise 86% of total fixed assets of $44 billion on a gross basis as of December 2017. The remaining depreciable assets of the Company, including non-railroad assets and assets under capital leases, are depreciated using the straight-line method on a per asset basis. Land is not depreciated. The group-life method aggregates assets with similar lives and characteristics into groups and depreciates each of these groups as a whole. When using the group-life method, an underlying assumption is that each group of assets, as a whole, is used and depreciated to the end of its group’s recoverable life. The Company currently utilizes different depreciable asset categories to account for depreciation expense for the railroad assets that are depreciated under the group-life method. By utilizing various depreciable categories, the Company can more accurately account for the use of its assets. All assets of the Company are depreciated on a time or life basis. The group-life method of depreciation closely approximates the straight-line method of depreciation. Additionally, due to the nature of most of its assets (e.g. track is one contiguous, connected asset), the Company believes that this is the most effective way to properly depreciate its assets. Estimated Useful Life Management performs a review of depreciation expense and useful lives on a regular basis. Under the group-life method, the service lives and salvage values for each group of assets are determined by completing periodic depreciation studies and applying management’s assumptions regarding the service lives of its properties. A depreciation study is the periodic review of asset service lives, salvage values, accumulated depreciation, and other related factors for group assets conducted by a third-party specialist, analyzed by the Company’s management and approved by the STB, the regulatory board that has broad jurisdiction over railroad practices. The STB requires depreciation studies be performed every three years for equipment assets (e.g. locomotives and freight cars) and every six years for road and track assets (e.g. bridges, signals, rail, ties, and ballast). The Company believes the frequency currently required by the STB provides adequate review of asset service lives and that a more frequent review would not result in a material change due to the long-lived nature of most of the assets. In 2016, the Company completed a depreciation study for its equipment assets. The Company plans to complete the next depreciation study for equipment assets in 2019 and road and track assets in 2020. Group-Life Assets Sales and Retirements Since the rail network is one contiguous, connected network it is impractical to maintain specific identification records for these assets. For track assets (e.g. rail, ties, and ballast), CSX utilizes a first-in, first-out approach to asset retirements. Equipment assets (e.g. locomotives and freight cars) are specifically identified at retirement. When an equipment asset is retired that has been depreciated using the group-life method, the cost is reduced from the cost base and recorded in accumulated depreciation. NOTE 6. Properties, continued For sales or retirements of assets depreciated under the group-life method that occur in the ordinary course of business, the asset cost (net of salvage value or sales proceeds) is charged to accumulated depreciation and no gain or loss is immediately recognized. This practice is consistent with accounting treatment normally prescribed under the group-life method. As part of the depreciation study, an assessment of the recorded amount of accumulated depreciation is made to determine if it is deficient (or in excess) of the appropriate amount indicated by the study. Any such deficiency (or excess), including any deferred gains or losses, is amortized as a component of depreciation expense over the remaining service life of the asset group until the next required depreciation study. Since the overall assumption with the group-life method is that the assets within the group on average have the same service life and characteristics, it is therefore concluded that the deferred gains and losses offset over time. For sales or retirements of assets depreciated under the group-life method that do not occur in the ordinary course of business, a gain or loss may be recognized if the sale or retirement meets each of the following three criteria: (i) it is unusual, (ii) it is material in amount, and (iii) it varies significantly from the retirement profile identified through our depreciation studies. No material gains or losses were recognized on the sale of assets depreciated using the group-life method in 2017, 2016, or 2015. Land and Straight-line Assets Sales and Retirements A gain or loss is recognized in operating income when we sell or retire land, land-related easements or assets depreciated under the straight-line method. In 2017 and 2016, the Company recognized gains on the sale of operating properties of $14 million and $110 million , respectively, which are recognized in materials, supplies and other on the consolidated statements of income. During 2015, the Company recognized a gain of $59 million related to the sale of non-operating easements, which is recognized in other income on the consolidated statements of income. (For additional information regarding cost reimbursements related to this sale, see Note 10, Other Income .) Impairment Review Properties and other long-lived assets are reviewed for impairment whenever events or business conditions indicate the carrying amount of such assets may not be fully recoverable. Initial assessments of recoverability are based on estimates of undiscounted future net cash flows associated with an asset or a group of assets in accordance with the Property, Plant, and Equipment Topic in the ASC. Where impairment is indicated, the assets are evaluated and their carrying amount is reduced to fair value based on discounted net cash flows or other estimates of fair value. In 2017, impairment expense of $25 million was recorded in materials, supplies and other expense primarily due to the discontinuation of certain in-progress projects. There were no material impairments recorded during 2016 or 2015.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Commitments The Company has various lease agreements with other parties with terms up to 30 years. Non-cancelable, long-term leases may include provisions for maintenance, options to purchase and options to extend the terms. Rent expense on operating leases is included in equipment and other rents on the consolidated income statements. The Company uses the straight-line method to recognize rent expense on operating leases that include escalations over their terms. These amounts are shown in the table below. Fiscal Years (Dollars in Millions) 2017 2016 2015 Rent Expense on Operating Leases (a) $ 78 $ 77 $ 86 (a) Prior year data has been reclassified to conform to the current presentation. At December 2017 , minimum rentals on land, buildings, track and equipment under operating leases are disclosed in the table below. Also, payments to Conrail for leases on shared rail infrastructure are included in these amounts. (See Note 12, Related Party Transactions ). (Dollars in Millions) Operating Sublease Net Lease Years Leases Income Commitments 2018 $ 68 $ (3 ) $ 65 2019 64 (3 ) 61 2020 50 (3 ) 47 2021 45 (3 ) 42 2022 41 (3 ) 38 Thereafter 128 (6 ) 122 Total $ 396 $ (21 ) $ 375 Purchase Commitments CSXT has a commitment under a long-term maintenance program agreement that covers a portion of CSXT’s fleet of locomotives. The program costs are based on the maintenance cycle for each covered locomotive, which is determined by the asset's age and type. Expected future costs may change as required maintenance schedules are revised and locomotives are placed into or removed from service. Under CSXT’s current obligations, the agreement will expire no earlier than 2031. At the end of 2016, the future commitment totaled $4.9 billion and after modifications to the agreement and ordinary activity throughout the year, the total commitment at December 31, 2017 was significantly reduced to $3.7 billion . In August 2017, the Company exercised certain rights under the agreement, which resulted in a reduction of locomotive fleet covered and reduced the future commitment at the end of the third quarter 2017. However, another modification was made on December 22, 2017 that superseded the previous modification, increasing the total commitment to $3.7 billion at the end of the year. About 50 percent of the locomotive fleet is covered under this agreement. NOTE 7. Commitments and Contingencies, continued The following table summarizes the number of locomotives covered and CSXT’s payments under the long-term maintenance program. Fiscal Years (Dollars in Millions) 2017 2016 2015 Amounts Paid $ 197 $ 230 $ 233 Number of Locomotives 2,062 2,243 2,310 As of December 2017, the Company has no outstanding locomotive purchase obligations. Annual payments related to the long-term locomotive maintenance program are estimated in the table below. Additionally, the Company has various other commitments to purchase technology, communications, railcar maintenance and other services from various suppliers. Total annual payments under all of these purchase commitments are also estimated in the table below. (Dollars in Millions) Locomotive Maintenance Payments Other Commitments Total 2018 $ 171 $ 119 $ 290 2019 162 67 229 2020 218 35 253 2021 223 35 258 2022 225 33 258 Thereafter 2,716 213 2,929 Total $ 3,715 $ 502 $ 4,217 Insurance The Company maintains numerous insurance programs with substantial limits for property damage (which includes business interruption) and third-party liability. A certain amount of risk is retained by the Company on each of the property and liability programs. The Company has a $25 million retention per occurrence for the non-catastrophic property program (such as a derailment) and a $50 million retention per occurrence for the liability and catastrophic property programs (such as hurricanes and floods). While the Company believes its insurance coverage is adequate, future claims could exceed existing insurance coverage or insurance may not continue to be available at commercially reasonable rates. NOTE 7. Commitments and Contingencies, continued Legal The Company is involved in litigation incidental to its business and is a party to a number of legal actions and claims, various governmental proceedings and private civil lawsuits, including, but not limited to, those related to fuel surcharge practices, tax matters, environmental and hazardous material exposure matters, FELA and labor claims by current or former employees, other personal injury or property claims and disputes and complaints involving certain transportation rates and charges. Some of the legal proceedings include claims for compensatory as well as punitive damages and others are, or are purported to be, class actions. While the final outcome of these matters cannot be predicted with certainty, considering, among other things, the legal defenses available and liabilities that have been recorded along with applicable insurance, it is currently the opinion of management that none of these pending items will have a material adverse effect on the Company's financial condition, results of operations or liquidity. An unexpected adverse resolution of one or more of these items, however, could have a material adverse effect on the Company's financial condition, results of operations or liquidity in that particular period. The Company is able to estimate a range of possible loss for certain legal proceedings for which a loss is reasonably possible in excess of reserves established. The Company has estimated this range to be $2 million to $117 million in aggregate at December 31, 2017 . This estimated aggregate range is based upon currently available information and is subject to significant judgment and a variety of assumptions. Accordingly, the Company's estimate will change from time to time, and actual losses may vary significantly from the current estimate. Fuel Surcharge Antitrust Litigation In May 2007, class action lawsuits were filed against CSXT and three other U.S.-based Class I railroads alleging that the defendants' fuel surcharge practices relating to contract and unregulated traffic resulted from an illegal conspiracy in violation of antitrust laws. In November 2007, the class action lawsuits were consolidated in federal court in the District of Columbia, where they are now pending. The suit seeks treble damages allegedly sustained by purported class members as well as attorneys' fees and other relief. Plaintiffs are expected to allege damages at least equal to the fuel surcharges at issue. In June 2012, the District Court certified the case as a class action. The decision was not a ruling on the merits of plaintiffs' claims, but rather a decision to allow the plaintiffs to seek to prove the case as a class. The defendant railroads petitioned the U.S. Court of Appeals for the D.C. Circuit for permission to appeal the District Court's class certification decision. In August 2013, the D.C. Circuit issued a decision vacating the class certification decision and remanded the case to the District Court to reconsider its class certification decision. On October 10, 2017, the District Court issued an order denying class certification. The U.S. Court of Appeals for the D.C. Circuit is reviewing the District Court’s decision. The District Court has not yet issued a further schedule on proceedings on the merits. CSXT believes that its fuel surcharge practices were arrived at and applied lawfully and that the case is without merit. Accordingly, the Company intends to defend itself vigorously. However, penalties for violating antitrust laws can be severe, and resolution of this matter or an unexpected adverse decision on the merits could have a material adverse effect on the Company's financial condition, results of operations or liquidity in that particular period. NOTE 7. Commitments and Contingencies, continued Environmental CSXT is indemnifying Pharmacia LLC (formerly known as Monsanto Company) for certain liabilities associated with real estate located in Kearny, New Jersey along the Lower Passaic River (the “Property”). The Property, which was formerly owned by Pharmacia, is now owned by CSXT. CSXT's indemnification and defense duties arise with respect to several matters. The U.S. Environmental Protection Agency ("EPA"), using its CERCLA authority, seeks cleanup and removal costs and other damages associated with the presence of hazardous substances in the 17 -mile Lower Passaic River Study Area (the "Study Area”). CSXT, on behalf of Pharmacia, and a significant number of other potentially responsible parties are together conducting a Remedial Investigation and Feasibility Study of the Study Area pursuant to an Administrative Settlement Agreement and Order on Consent with the EPA. In March 2016, EPA issued its Record of Decision detailing the agency’s mandated remedial process for the lower 8 miles of the Study Area, which was based on a Focused Feasibility Study. EPA has estimated that it will take the potentially responsible parties approximately ten years to complete the work. EPA is currently in discussions with various potentially responsible parties to seek their agreement to pay for or perform the work. At a later date, EPA will select a remedy for the remainder of the Study Area and is expected to again seek the participation of private parties to implement the selected remedy using EPA’s CERCLA authority to compel such participation, if necessary. CSXT is also defending and indemnifying Pharmacia in a cooperative natural resource damages assessment process related to the Property. Based on currently available information, the Company does not believe any indemnification or remediation costs potentially allocable to CSXT with respect to the Property and the Study Area would be material to the Company's financial condition, results of operations or liquidity.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Employee Benefit Plans	Employee Benefit Plans The Company sponsors defined benefit pension plans principally for salaried, management personnel. For employees hired prior to 2003 , the plans provide eligible employees with retirement benefits based predominantly on years of service and compensation rates near retirement. For employees hired in 2003 or thereafter, benefits are determined based on a cash balance formula, which provides benefits by utilizing interest and pay credits based upon age, service and compensation. In addition to these plans, the Company sponsors a post-retirement medical plan and a life insurance plan that provide certain benefits to full-time, salaried, management employees hired prior to 2003 , upon their retirement if certain eligibility requirements are met. Eligible retirees who are age 65 years or older (Medicare-eligible) are covered by a health reimbursement arrangement, which is an employer-funded account that can be used for reimbursement of eligible medical expenses. Eligible retirees younger than 65 years (non-Medicare eligible) are covered by a self-insured program partially funded by participating retirees. The life insurance plan is non-contributory. NOTE 8. Employee Benefit Plans, continued The Company engages independent actuaries to compute the amounts of liabilities and expenses relating to these plans subject to the assumptions that the Company determines are appropriate based on historical trends, current market rates and future projections. These amounts are reviewed by management. In order to perform this valuation, the actuaries are provided with the details of the population covered at the beginning of the year, summarized in the table below, and projects that population forward to the end of the year . Summary of Participants as of January 1, 2017 Pension Plans Post-retirement Medical Plan Active Employees 3,744 458 Retirees and Beneficiaries 12,723 9,940 Other (a) 3,591 36 Total 20,058 10,434 (a) For pension plans, the other category consists mostly of terminated but vested former employees. For post-retirement plans, the other category consists of employees on long-term disability that have not yet retired. The benefit obligation for these plans represents the liability of the Company for current and retired employees and is affected primarily by the following: • service cost (benefits attributed to employee service during the period); • interest cost (interest on the liability due to the passage of time); • actuarial gains/losses (experience during the year different from that assumed and changes in plan assumptions); and • benefits paid to participants. Cash Flows Plan assets are amounts that have been segregated and restricted to provide qualified pension plan benefits and include amounts contributed by the Company and amounts earned from invested contributions, net of benefits paid. Qualified pension plan obligations are funded in accordance with regulatory requirements and with an objective of meeting or exceeding minimum funding requirements necessary to avoid restrictions on flexibility of plan operation and benefit payments. The Company funds the cost of the post-retirement medical and life insurance benefits as well as nonqualified pension benefits on a pay-as-you go basis. No qualified pension plan contributions were made during 2015 and 2017. Although no contributions to the Company's qualified pension plans were required, CSX made voluntary contributions totaling $250 million during 2016. No contributions to the Company's qualified pension plans are expected in 2018 . NOTE 8. Employee Benefit Plans, continued Future expected benefit payments are as follows: Expected Cash Flows (Dollars in Millions) Pension Benefits Post-retirement Benefits 2018 $ 198 $ 38 2019 193 28 2020 189 26 2021 186 24 2022 183 22 2023-2026 888 76 Total $ 1,837 $ 214 Plan Assets The CSX Investment Committee (the “Investment Committee”), whose members are selected by the Chief Financial Officer, is responsible for oversight and investment of plan assets. The Investment Committee utilizes an investment asset allocation strategy that is monitored on an ongoing basis and updated periodically in consideration of plan or employee changes, or changing market conditions. Periodic studies provide an extensive modeling of asset investment return in conjunction with projected plan liabilities and seek to evaluate how to maximize return within the constraints of acceptable risk. The current asset allocation targets 70% equity investments and 30% fixed income investments and cash. Within equity, a further target is currently established for 42% of total plan assets in domestic equity and 28% in international equity. Allocations are evaluated for levels within 3% of targeted allocations and are adjusted quarterly as necessary. The distribution of pension plan assets as of the measurement date is shown in the table below, and these assets are reported net of pension liabilities on the balance sheet. December 2017 December 2016 Percent of Percent of (Dollars in Millions) Amount Total Assets Amount Total Assets Equity $ 2,060 73 % $ 1,806 71 % Fixed Income 729 26 665 26 Cash and Cash Equivalents 44 1 68 3 Total $ 2,833 100 % $ 2,539 100 % Under the supervision of the Investment Committee, individual investments or fund managers are selected in accordance with standards of prudence applicable to asset diversification and investment suitability. The Company also selects fund managers with differing investment styles and benchmarks their investment returns against appropriate indices. Fund investment performance is continuously monitored. Acceptable performance is determined in the context of the long-term return objectives of the fund and appropriate asset class benchmarks. NOTE 8. Employee Benefit Plans, continued Within the Company's equity funds, domestic stock is diversified among large and small capitalization stocks. International stock is diversified in a similar manner as well as in developed versus emerging markets stocks. Guidelines established with individual managers limit investment by industry sectors, individual stock issuer concentration and the use of derivatives and CSX securities. Fixed income securities guidelines established with individual managers specify the types of allowable investments, such as government, corporate and asset-backed bonds, target certain allocation ranges for domestic and foreign investments and limit the use of certain derivatives. Additionally, guidelines stipulate minimum credit quality constraints and any prohibited securities. For detailed information regarding the fair value of pension assets, see Note 13, Fair Value Measurements . Benefit Obligation, Plan Assets and Funded Status Changes in benefit obligation and the fair value of plan assets for the 2017 and 2016 calendar plan years are as follows: Pension Benefits Post-retirement Benefits Plan Year Plan Year Plan Year Plan Year (Dollars in Millions) 2017 2016 2017 2016 Actuarial Present Value of Benefit Obligation Accumulated Benefit Obligation $ 2,873 $ 2,717 N/A N/A Projected Benefit Obligation 3,002 2,871 $ 250 $ 274 Change in Projected Benefit Obligation: Projected Benefit Obligation at Beginning of Plan Year $ 2,871 $ 2,860 $ 274 $ 314 Service Cost 36 48 2 2 Interest Cost 92 119 7 12 Plan Participants' Contributions — — 7 6 Workforce Reduction Program/Curtailment 58 — 13 — Actuarial Loss (Gain) 163 20 (17 ) (22 ) Benefits Paid (218 ) (176 ) (36 ) (38 ) Benefit Obligation at End of Plan Year $ 3,002 $ 2,871 $ 250 $ 274 Change in Plan Assets: Fair Value of Plan Assets at Beginning of Plan Year $ 2,539 $ 2,309 $ — $ — Actual Return on Plan Assets 467 139 — — Qualified Employer Contributions — 250 — — Non-qualified Employer Contributions 45 17 29 32 Plan Participants' Contributions — — 7 6 Benefits Paid (218 ) (176 ) (36 ) (38 ) Fair Value of Plan Assets at End of Plan Year 2,833 2,539 — — Funded Status at End of Plan Year $ (169 ) $ (332 ) $ (250 ) $ (274 ) NOTE 8. Employee Benefit Plans, continued For qualified plan funding purposes, assets and discounted liabilities are measured in accordance with the Employee Retirement Income Security Act ("ERISA"), as well as other related provisions of the IRC and related regulations. Under these funding provisions and the alternative measurements available thereunder, the Company estimates its unfunded obligation for qualified plans on an annual basis. In accordance with Compensation-Retirement Benefits Topic in the ASC, an employer must recognize the funded status of a pension or other post-retirement benefit plan by recording a liability (underfunded plan) or asset (overfunded plan) for the difference between the projected benefit obligation (or the accumulated post-retirement benefit obligation for a post-retirement benefit plan) and the fair value of plan assets at the plan measurement date. Amounts related to pension and post-retirement benefits recorded in other long-term assets, labor and fringe benefits payable and other long-term liabilities on the balance sheet are as follows: Pension Benefits Post-retirement Benefits December December December December (Dollars in Millions) 2017 2016 2017 2016 Amounts Recorded in Consolidated Balance Sheets: Long-term Assets (a) $ 57 $ 9 $ — $ — Current Liabilities (15 ) (15 ) (38 ) (39 ) Long-term Liabilities (211 ) (326 ) (212 ) (235 ) Net Amount Recognized in Consolidated Balance Sheets $ (169 ) $ (332 ) $ (250 ) $ (274 ) (a) Long-term assets as of December 2017 and 2016 relate to qualified pension plans where assets exceed projected benefit obligations. At December 2017, the fair value of plan assets for all qualified pension plans exceeded the benefit obligation. At December 2017 , benefit obligations of the unfunded CSX non-qualified pension plans is disclosed below. Aggregate (Dollars in Millions) Fair Value Aggregate Benefit Obligations in Excess of Plan Assets of Plan Assets Benefit Obligation Projected Benefit Obligation $ — $ (226 ) Accumulated Benefit Obligation — (216 ) NOTE 8. Employee Benefit Plans, continued Net Benefit Expense The following table describes the components of expense/(income) related to net benefit expense recorded in labor and fringe on the income statement. Pension Benefits Fiscal Years Post-retirement Benefits Fiscal Years (Dollars in Millions) 2017 2016 2015 2017 2016 2015 Service Cost $ 36 $ 48 $ 45 $ 2 $ 2 $ 2 Interest Cost 92 119 116 7 12 12 Expected Return on Plan Assets (171 ) (157 ) (162 ) — — — Amortization of Net Loss 41 48 70 — 3 4 Amortization of Prior Service Cost — — — — — (1 ) Net Periodic Benefit Expense (2 ) 58 69 9 17 17 Special Termination Benefits - Workforce Reduction Program/Curtailment 60 — 7 13 — — Settlement Loss (Gain) 11 (1 ) (2 ) — — — Total Expense $ 69 $ 57 $ 74 $ 22 $ 17 $ 17 As a result of the management workforce reduction programs initiated in 2017, $85 million in charges were incurred related to special termination benefits, curtailment and settlement changes. In 2017, the Company recorded special termination pension benefits of $56 million and remeasured the pension and other post-retirement benefits assets and obligations and recorded a curtailment loss of $4 million and $13 million , respectively, in restructuring charge on the income statement. Pension settlement losses (gains) were recognized as a result of lump-sum payments to retirees exceeding the sum of the plan’s service and interest cost. The Company recorded an $11 million net settlement loss in 2017, of which a $12 million loss resulted from the retirements of former executives and is reported in restructuring charge on the income statement. The other settlement gains in 2017, 2016 and 2015 were from one of the Company’s qualified pension plans with insignificant balances and were recorded in labor and fringe expense on the income statement. The special termination benefits in 2015 resulted from the management workforce reduction programs initiated in 2014. For additional information regarding the management workforce reductions, see Note 1, Nature of Operations and Significant Accounting Policies. NOTE 8. Employee Benefit Plans, continued Pension and Other Post-Employment Benefits Adjustments The following table shows the pre-tax change in other comprehensive loss (income) attributable to the components of net expense and the change in benefit obligation for CSX for pension and other post-employment benefits. (Dollars in Millions) Pension Benefits Post-retirement Benefits Components of Other Comprehensive December December December December Loss (Income) 2017 2016 2017 2016 Recognized in the balance sheet (Gains) Losses $ (131 ) $ 38 $ (17 ) $ (22 ) Expense (Income) recognized in the income statement Amortization of net losses (a) $ 41 $ 48 $ — $ 3 Settlement gain 11 (1 ) — — Curtailment loss 4 — — — (a) Amortization of net losses estimated to be expensed for 2018 is approximately $43 million for pension benefits. As of December 2017 , the balances of pre-tax losses to be amortized related to the Company's pension and post-retirement obligations are $705 million and $7 million , respectively. These amounts are included in accumulated other comprehensive loss, a component of shareholders’ equity. Assumptions The expected long-term average rate of return on plan assets reflects the average rate of earnings expected on the funds invested, or to be invested, to provide for benefits included in the projected benefit obligation. In estimating that rate, the Company gives appropriate consideration to the returns being earned by the plan assets in the funds and the rates of return expected to be available for reinvestment as well as the current and projected asset mix of the funds. Management balances market expectations obtained from various investment managers and economists with both market and actual plan historical returns to develop a reasonable estimate of the expected long-term rate of return on assets. This assumption is reviewed annually and adjusted as deemed appropriate. Beginning in 2017, the Company measured the service cost and interest cost components of the net pension and post-retirement benefits expense by using individual spot rates matched with separate cash flows for each future year instead of a single weighted-average discount rate approach, which has been used in prior years. The Company made this change to improve the correlation between projected pension and post-retirement benefit obligation cash flows and the corresponding spot discount rates and to provide a more precise measurement of service and interest costs. Under the spot rate approach, individual spot discount rates along the same high-quality corporate bonds yield curve used to measure the pension and post-retirement benefit obligations are applied to the relevant projected cash flows at the relevant maturity. The use of the spot rate approach does not affect the measurement of the pension and post-retirement benefits obligations. The Company accounted for this change on a prospective basis as a change in accounting estimate. For 2017, the adoption of the spot rate approach decreased the Company's net pension and post-retirement benefits expense by approximately $25 million compared to the approach applicable in prior years. NOTE 8. Employee Benefit Plans, continued The weighted averages of assumptions used by the Company to value its pension and post-retirement obligations were as follows: Pension Benefits Post-retirement Benefits 2017 2016 2017 2016 Expected Long-term Return on Plan Assets: Benefit Cost for Current Plan Year 6.75 % 7.00 % N/A N/A Benefit Cost for Subsequent Plan Year 6.75 % 6.75 % N/A N/A Discount Rates: Benefit Cost for Plan Year — % — % — % — % Service Cost for Plan Year 4.26 % (a) 4.30 % 4.11 % (b) 3.85 % Interest Cost for Plan Year 3.26 % (a) 4.30 % 2.78 % (b) 3.85 % Benefit Obligation at End of Plan Year 3.56 % 4.08 % 3.34 % 3.71 % Salary Scale Inflation 4.60 % 4.60 % N/A N/A (a) The pension benefits service cost and interest cost for 2017 were based on a weighted average discount rate of 4.35% and 3.37% , respectively, prior to the management workforce reduction program initiated in 2017 and were reduced to 4.26% and 3.26% , respectively, after the Company remeasured the pension benefits obligation and pension plan assets in the second quarter of 2017. (b) The post-retirement benefits service cost and interest cost for 2017 were based on a weighted average discount rate of 4.20% and 2.88% , respectively, prior to the management workforce reduction program initiated in 2017 and were reduced to 4.11% and 2.78% , respectively, after the Company remeasured the other post-retirement benefits obligation in the first quarter of 2017. The impact of the health care cost trend rate is immaterial to the post-retirement benefit cost and obligation due to the plan's health reimbursement arrangement that covers Medicare-eligible retirees. Other Plans Under collective bargaining agreements, the Company participates in a multi-employer benefit plan, which provides certain post-retirement health care and life insurance benefits to eligible contract employees. Premiums under this plan are expensed as incurred and amounted to $40 million , $35 million and $32 million in 2017 , 2016 and 2015 , respectively. The Company maintains savings plans for virtually all full-time salaried employees and certain employees covered by collective bargaining agreements. Expense associated with these plans was $39 million , $35 million and $36 million for 2017 , 2016 and 2015 , respectively, and is included in labor and fringe expense on the consolidated income statement.

Debt and Credit Agreements

Debt and Credit Agreements	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt and Credit Agreements	Debt and Credit Agreements Debt at December 2017 and December 2016 is shown in the table below. For information regarding the fair value of debt, see Note 13, Fair Value Measurements. Maturity at December Average Interest Rates at December December December (Dollars in Millions) 2017 2017 2017 2016 Notes 2020-2066 4.3% $ 11,591 $ 11,055 Equipment Obligations (a) 2018-2023 6.3% 213 232 Capital Leases 2018-2026 16.2% 5 6 Subtotal Long-term Debt (including current portion) $ 11,809 $ 11,293 Less Debt Due within One Year (19 ) (331 ) Long-term Debt (excluding current portion) $ 11,790 $ 10,962 (a) Equipment obligations are secured by an interest in certain railroad equipment. Debt Issuance & Early Redemption of Long-term Debt In May 2017, CSX issued $850 million of 3.25% notes due 2027. These notes are included in the consolidated balance sheets under long-term debt and may be redeemed by the Company at any time. The net proceeds have been or will be used for general corporate purposes, which may include repurchases of CSX's common stock, capital investment, working capital requirements, improvement in productivity and other cost reductions at CSX’s major transportation units. During 2016, the Company issued $2.2 billion of new debt and repurchased $1.4 billion of certain notes that were expected to mature in 2017, 2018 and 2019 resulting in a net increase in debt of $800 million related to these transactions. CSX issued $700 million of 2.60% notes due 2026 , $800 million of 3.80% notes due 2046 , and $700 million of 4.25% notes due 2066 (collectively, the “2016 issuances”). These notes are included in the consolidated balance sheets under long-term debt and may be redeemed by the Company at any time at the applicable redemption premium. The net proceeds of the 2016 issuances were used to fully redeem $300 million of 5.60% notes that otherwise would have matured on May 1, 2017 ; $600 million of 6.25% notes that otherwise would have matured on March 15, 2018 ; and $500 million of 7.375% notes that otherwise would have matured on February 1, 2019 . The remaining proceeds were used for general corporate purposes, which may include repurchases of CSX’s common stock, capital investment, pension contributions, working capital requirements, improvements in productivity and other cost reductions at CSX’s major transportation units. The transactions noted above were determined to be an extinguishment of the existing debt, resulting in recognition of $115 million of debt repurchase expense in 2016 related to $1.4 billion of note repayments. NOTE 9. Debt and Credit Agreements, continued Long-term Debt Maturities (Net of Discounts, Premiums and Issuance Costs) (Dollars in Millions) Maturities as of Fiscal Years Ending December 2017 2018 $ 19 2019 18 2020 745 2021 371 2022 162 Thereafter 10,494 Total Long-term Debt Maturities, including current portion $ 11,809 Credit Facilities CSX has a $1 billion unsecured, revolving credit facility backed by a diverse syndicate of banks. This facility expires in May 2020 , and as of the date of this filing, the Company has no outstanding balances under this facility. The facility allows borrowings at floating (LIBOR-based) interest rates, plus a spread, depending upon CSX's senior unsecured debt ratings. LIBOR is the London Interbank Offered Rate which is a daily reference rate based on the interest rates at which banks offer to lend unsecured funds. Commitment fees and interest rates payable under the facility were similar to fees and rates available to comparably rated investment-grade borrowers. At December 2017, CSX was in compliance with all covenant requirements under the facility. Receivables Securitization Facility The Company has a receivables securitization facility with a three -year term scheduled to expire in September 2019 . The purpose of this facility is to provide an alternative to commercial paper and a low cost source of short-term liquidity of up to $200 million , depending on eligible receivables balances. Under the terms of this facility, CSXT transfers eligible third-party receivables to CSX Trade Receivables, LLC, a bankruptcy-remote special purpose subsidiary. A separate subsidiary of CSX services the receivables. Upon transfer, the receivables become assets of CSX Trade Receivables and are not available to the creditors of CSX or any of its other subsidiaries. In the event CSX Trade Receivables draws under this facility, the Company will record an equivalent amount of debt on its consolidated financial statements. As of December 30, 2017 and the date of this filing, the Company has no outstanding balances under this facility.

Other Income - Net

Other Income - Net	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Other Income - Net	Other Income - Net The Company derives income from items that are not considered operating activities. Income from these items is reported net of related expense. Miscellaneous income (expense) includes investment gains and losses, certain non-operating equity earnings or losses and other non-operating activities and may fluctuate due to timing. As substantially all real estate activities are focused on supporting railroad operations, beginning in first quarter 2017, all results of these activities are included in operating income. Previously, these activities were classified as operating or non-operating based on the nature of the activity. As the results of these activities were not material for any periods presented, prior periods have not been reclassified. Interest Income increased from 2016 to 2017 primarily due to higher yields on investment securities. Income from real estate operations were recorded as part of operating expenses during 2017. Other income – net consisted of the following: Fiscal Years (Dollars in Millions) 2017 2016 2015 Interest Income $ 13 $ 10 $ 6 Income from Non-operating Real Estate Activities — 27 83 Miscellaneous Income (Expense) 8 9 9 Total Other Income (Expense) - Net $ 21 $ 46 $ 98 Gross Revenue from Real Estate Operations included above $ — $ 56 $ 104

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Earnings before income taxes of $3.1 billion , $2.7 billion and $3.1 billion for fiscal years 2017 , 2016 and 2015 , respectively, represent earnings from domestic operations. The breakdown of income tax expense between current and deferred is as follows: Fiscal Years (Dollars in Millions) 2017 2016 2015 Current: Federal $ 787 $ 540 $ 619 State 117 82 95 Subtotal Current 904 622 714 Deferred: Federal (3,277 ) 355 414 State 44 50 42 Subtotal Deferred (3,233 ) 405 456 Total $ (2,329 ) $ 1,027 $ 1,170 NOTE 11. Income Taxes, continued Income tax expense reconciled to the tax computed at statutory rates is presented in the table below. With the enactment of the Tax Cuts and Jobs Act (the "Act" or "tax reform") on December 22, 2017, the Company's 2017 financial results included a $3.5 billion , or $3.81 per share, non-cash reduction in income tax expense, primarily resulting from revaluing the Company's net deferred tax liabilities to reflect the recently enacted 21% federal corporate tax rate effective January 1, 2018. These estimates are based on the Company's initial analysis of the Act and may be adjusted in future periods as required. The Act has significant complexity and implementation guidance from the Internal Revenue Service, clarifications of state tax law and the completion of the Company’s 2017 tax return filings could all impact these estimates. The Company does not believe potential adjustments in future periods would materially impact the Company's financial condition or results of operations. The provisions of the Act related to foreign earnings will not impact CSX. The Company's affiliates also revalued their deferred tax liabilities to reflect the lower federal corporate tax rate, which resulted in the Company recognizing a benefit of $142 million , or $0.10 per share after-tax, in equity earnings of affiliates, which is included in operating income. (See additional discussion over equity earnings of affiliates in Note 12, Related Parties and Affiliates .) In addition to the tax benefit related to tax reform, the Company recorded a 2017 income tax benefit of $21 million primarily as a result of the additional tax benefit associated with vesting of share-based awards, state legislative changes, a change in the apportionment of state taxable income and the related impact on the valuation of deferred taxes, and the settlement of certain state tax matters . In 2016, the Company recorded an income tax expense adjustment of $10 million as a result of a change in the apportionment of state income taxes and the related impact on the valuation of deferred taxes as well as a $7 million tax benefit as a result of federal and state legislative changes. In 2015, the Company recorded a tax benefit of $4 million primarily as a result of federal and state legislative changes as well as the resolution of federal and state tax matters. Fiscal Years (Dollars In Millions) 2017 2016 2015 Federal Income Taxes $ 1,100 35.0 % $ 959 35.0 % $ 1,098 35.0 % State Income Taxes 102 3.2 % 83 3.0 % 86 2.7 % Deferred Tax Rate Change (3,506 ) (111.6 )% — — % — — % Other (25 ) (0.8 )% (15 ) (0.5 )% (14 ) (0.4 )% Income Tax (Benefit) Expense/Rate $ (2,329 ) (74.2 )% $ 1,027 37.5 % $ 1,170 37.3 % NOTE 11. Income Taxes, continued The significant components of deferred income tax assets and liabilities include: 2017 2016 (Dollars in Millions) Assets Liabilities Assets Liabilities Pension Plans $ 41 $ — $ 125 $ — Other Employee Benefit Plans 182 — 272 — Accelerated Depreciation — 6,576 — 9,925 Other 657 722 225 293 Total $ 880 $ 7,298 $ 622 $ 10,218 Net Deferred Income Tax Liabilities $ 6,418 $ 9,596 The primary factors in the change in year-end net deferred income tax liability balances include: • annual provision for deferred income tax expense including the impact of the recently enacted federal corporate tax rate change from 35 percent to 21 percent , and • accumulated other comprehensive income/loss. The Company files a consolidated federal income tax return, which includes its principal domestic subsidiaries. CSX and its subsidiaries are subject to U.S. federal income tax as well as income tax of multiple state jurisdictions. CSX participated in a contemporaneous IRS audit of tax years 2016 and 2017 . Federal examinations of original federal income tax returns for all years through 2015 are resolved. As of December 2017 , 2016 and 2015 , the Company had approximately $24 million , $25 million and $23 million , respectively, of total unrecognized tax benefits as a result of uncertain tax positions. Net tax benefits of $19 million , $16 million and $15 million in 2017 , 2016 and 2015 , respectively, could favorably impact the effective income tax rate in each year. The Company does not expect that unrecognized tax benefits as of December 2017 for various state and federal income tax matters will significantly change over the next 12 months. The final outcome of these uncertain tax positions is not yet determinable. The change to the total gross unrecognized tax benefits and prior year audit resolutions of the Company during the fiscal year ended December 2017 is reconciled in the table below. Unrecognized Tax Benefits: Fiscal Year (Dollars in Millions) 2017 2016 2015 Balance at beginning of the year $ 25 $ 23 $ 21 Additions based on tax positions related to current year 1 1 1 Additions based on tax positions related to prior years 4 4 4 Reductions based on tax positions related to prior years — — — Settlements with taxing authorities (4 ) — 1 Lapse of statute of limitations (2 ) (3 ) (4 ) Balance at end of the year $ 24 $ 25 $ 23 NOTE 11. Income Taxes, continued CSX’s continuing practice is to recognize net interest and penalties related to income tax matters in income tax expense. Included in the consolidated income statements are expenses of $3 million , $2 million and $2 million in 2017, 2016 and 2015 , respectively, for changes to reserves for interest and penalties for all prior year tax positions. The Company had $6 million , $6 million and $4 million accrued for interest and penalties at 2017 , 2016 and 2015 , respectively, for all prior year tax positions.

Related Parties and Affiliates

Related Parties and Affiliates	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Parties and Affiliates	Related Parties and Affiliates Conrail Through a limited liability company, CSX and Norfolk Southern Corporation (“NS”) jointly own Conrail. CSX has a 42% economic interest and 50% voting interest in the jointly-owned entity, and NS has the remainder of the economic and voting interests. Pursuant to the Investments-Equity Method and Joint Venture Topic in the ASC, CSX applies the equity method of accounting to its investment in Conrail. Conrail owns rail infrastructure and operates for the joint benefit of CSX and NS. This is known as the shared asset area. Conrail charges fees for right-of-way usage, equipment rentals and transportation, switching and terminal service charges in the shared asset area. These expenses are included in materials, supplies and other on the consolidated income statements. Future minimum lease payments due to Conrail under the shared asset area agreements are shown in the table below. (Dollars in Millions) Conrail Shared Years Asset Agreement 2018 $ 27 2019 27 2020 27 2021 27 2022 27 Thereafter 48 Total $ 183 Also, included in equity earnings of affiliates are CSX’s 42 percent share of Conrail’s income and its amortization of the fair value write-up arising from the acquisition of Conrail and certain other adjustments. The amortization primarily represents the additional after-tax depreciation expense related to the write-up of Conrail’s fixed assets when the original purchase price, from the 1997 acquisition of Conrail, was allocated based on fair value. This write-up of fixed assets resulted in a difference between CSX's investment in Conrail and its share of Conrail's underlying net equity, which is $347 million as of December 2017 . NOTE 12. Related Parties and Affiliates, continued The following table discloses amounts related to Conrail. Purchase price amortization and equity earnings are included in equity earnings of affiliates and all other amounts in the table are included in materials, supplies and other expenses on the Company’s consolidated income statements. Fiscal Years (Dollars in Millions) 2017 2016 2015 Rents, fees and services $ 120 $ 114 $ 123 Purchase price amortization and other 4 4 4 Equity earnings of Conrail (58 ) (37 ) (33 ) Total Conrail Expense $ 66 $ 81 $ 94 As required by the Related Party Disclosures Topic in the ASC, the Company has identified amounts below owed to Conrail, or its subsidiaries, representing liabilities under the operating, equipment and shared area agreements with Conrail. In 2014, the Company also executed two promissory notes with a subsidiary of Conrail which were included in long-term debt on the consolidated balance sheets. Interest expense from these promissory notes was $6 million for 2017 , 2016 and 2015 , respectively. December December (Dollars in Millions) 2017 2016 Balance Sheet Information: CSX payable to Conrail $ 123 $ 91 Promissory notes payable to Conrail subsidiary 2.89% CSX promissory note due October 2044 73 73 2.89% CSXT promissory note due October 2044 151 151 TTX Company TTX Company ("TTX") is a privately-held corporation engaged in the business of providing its owner-railroads with standardized fleets of intermodal, automotive and general use railcars at time and mileage rates. CSX owns about 20 percent of TTX's common stock, and the remaining is owned by the other leading North American railroads and their affiliates. CSX's investment in TTX is $626 million and is included in affiliates and other companies in the consolidated balance sheet. Pursuant to the Investments-Equity Method topic in the ASC, CSX applies the equity method of accounting to its investment in TTX. NOTE 12. Related Parties and Affiliates, continued As required by the Related Party Disclosures Topic in the ASC, the following table discloses amounts related to TTX. Car hire rents are included in equipment and other rents expense and equity earnings are included in equity earnings of affiliates in the Company’s consolidated income statements. Also included below is balance sheet information related to CSX's payable to TTX, which represents car rental liabilities. Fiscal Years (Dollars in Millions) 2017 2016 2015 Income statement information: Car hire rents $ 237 $ 233 $ 218 Equity earnings of TTX (157 ) (26 ) (20 ) Total TTX expense $ 80 $ 207 $ 198 December December Balance sheet information: 2017 2016 CSX payable to TTX $ 43 $ 47 Tax Reform Effect on Equity Earnings of Affiliates Due to the enactment of tax reform, the Company recognized a benefit of $142 million , or $0.10 per share after-tax, in its equity earnings of affiliates. This benefit was primarily the result of the Company's affiliates (primarily TTX and Conrail) revaluing their deferred tax liabilities to reflect the lower federal corporate tax rate, which favorably impacted their net earnings for 2017. (See additional discussion over tax reform in Note 11, Income Taxes.)

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Fin ancial Instruments Topic in the ASC requires disclosures about fair value of financial instruments in annual reports as well as in quarterly reports. For CSX, this statement applies to certain investments, pension plan assets and long-term debt. Also, the Fair Value Measurements and Disclosures Topic in the ASC clarifies the definition of fair value for financial reporting, establishes a framework for measuring fair value and requires additional disclosures about the use of fair value measurements. Various inputs are considered when determining the value of the Company's investments, pension plan assets and long-term debt. The inputs or methodologies used for valuing securities are not necessarily an indication of the risk associated with investing in these securities. These inputs are summarized in the three broad levels listed below: • Level 1 – observable market inputs that are unadjusted quoted prices for identical assets or liabilities in active markets; • Level 2 – other significant observable inputs (including quoted prices for similar securities, interest rates, credit risk, etc.); and • Level 3 – significant unobservable inputs (including the Company’s own assumptions about the assumptions market participants would use in determining the fair value of investments). The valuation methods described below may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Company believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date. Investments The Company's investment assets, valued with assistance from a third-party trustee, consist of certificates of deposits, commercial paper, corporate bonds and government securities and are carried at fair value on the consolidated balance sheet per the Fair Value Measurements and Disclosures Topic in the ASC. There are several valuation methodologies used for those assets as described below: • Certificates of Deposit and Commercial Paper (Level 2): Valued at amortized cost, which approximates fair value; • Corporate Bonds and Government Securities (Level 2): Valued using broker quotes that utilize observable market inputs; and The Company's investment assets are carried at fair value on the consolidated balance sheets as summarized in the following table. All of the inputs used to determine the fair value of the Company's investments are Level 2 inputs. The amortized cost basis of these investments was $91 million and $500 million as of December 31, 2017 and December 30, 2016 , respectively. NOTE 13. Fair Value Measurements, continued Fiscal Years 2017 2016 (Dollars in Millions) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Certificates of Deposit and Commercial Paper $ — $ — $ — $ — $ — $ 415 $ — $ 415 Corporate Bonds — 61 — 61 — 63 — 63 Government Securities — 34 — 34 — 22 — 22 Total investments at fair value $ — $ 95 $ — $ 95 $ — $ 500 $ — $ 500 These investments have the following maturities and are represented on the consolidated balance sheet within short-term investments for investments with maturities of less than one year, and other long-term assets for investments with maturities of one year and greater: (Dollars in Millions) December 2017 December 2016 Less than 1 year $ 18 $ 417 1 - 2 years 3 12 2 - 5 years 8 4 Greater than 5 years 66 67 Total investments at fair value $ 95 $ 500 Long-term Debt Long-term debt is reported at carrying amount on the consolidated balance sheets and is the Company's only financial instrument with fair values significantly different from their carrying amounts. The majority of the Company's long-term debt is valued with assistance from a third party that utilizes closing transactions, market quotes or market values of comparable debt. For those instruments not valued by the third party, the fair value has been estimated by applying market rates of similar instruments to the scheduled contractual debt payments and maturities. These market rates are provided by the same third party. All of the inputs used to determine the fair value of the Company's long-term debt are Level 2 inputs. The fair value of outstanding debt fluctuates with changes in a number of factors. Such factors include, but are not limited to, interest rates, market conditions, credit ratings, values of similar financial instruments, size of the transaction, cash flow projections and comparable trades. Fair value will exceed carrying value when the current market interest rate is lower than the interest rate at which the debt was originally issued. The fair value of a company's debt is a measure of its current value under present market conditions. It does not impact the financial statements under current accounting rules. NOTE 13. Fair Value Measurements, continued The fair value and carrying value of the Company's long-term debt is as follows: (Dollars in Millions) December 2017 December 2016 Long-term Debt (Including Current Maturities): Fair Value $ 13,220 $ 12,096 Carrying Value 11,809 11,293 Pension Plan Assets Pension plan assets are reported at fair value, net of pension liabilities, on the consolidated balance sheet. The Investment Committee targets an allocation of pension assets to be generally 70% equity and 30% fixed income. There are several valuation methodologies used for those assets as described below. Investments in the Fair Value Hierarchy • Common stock (Level 1): Valued at the closing price reported on the active market on which the individual securities are traded on the last day of the year and classified in Level 1 of the fair value hierarchy. • Mutual funds (Level 1) : Valued at the net asset value of shares held at year end based on quoted market prices determined in an active market. These assets are classified in Level 1 of the fair value hierarchy. • Corporate bonds, government securities, asset-backed securities and derivatives (Level 2): Valued using price evaluations reflecting the bid and/or ask sides of the market for a similar investment at year end. Asset-backed securities include commercial mortgage-backed securities and collateralized mortgage obligations. These assets are classified in Level 2 of the fair value hierarchy. Investments Measured at Net Asset Value • Partnerships: Net asset value of private equity is based on the fair market values associated with the underlying investments at year end. These funds have redemption restrictions that require advanced notice of 15 business days. • Common collective trust funds: This class consists of private funds that invest in government and corporate securities and various short-term debt instruments and are measured at net asset value to estimate the fair value of the investments. The net asset value of the investments is determined by reference to the fair value of the underlying securities, which are valued primarily through the use of directly or indirectly observable inputs. These funds have redemption restrictions that require advanced notice of up to 15 business days. NOTE 13. Fair Value Measurements, continued The pension plan assets at fair value by level, within the fair value hierarchy, as of calendar plan years 2017 and 2016 are shown in the table below. For additional information related to pension assets, see Note 8, Employee Benefit Plans. Fiscal Years 2017 2016 (Dollars in Millions) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Common Stock $ 1,022 $ — $ — $ 1,022 $ 940 $ — $ — $ 940 Mutual funds 14 — — 14 12 — — 12 Cash equivalents 2 — — 2 1 — — 1 Corporate bonds — 537 — 537 — 497 — 497 Government securities — 169 — 169 — 141 — 141 Asset-backed securities — 9 — 9 — 14 — 14 Derivatives and other — 11 — 11 — 11 — 11 Total investments in the fair value hierarchy $ 1,038 $ 726 $ — $ 1,764 $ 953 $ 663 $ — $ 1,616 Investments measured at net asset value (a) n/a n/a n/a $ 1,069 n/a n/a n/a $ 923 Investments at fair value $ 1,038 $ 726 $ — $ 2,833 $ 953 $ 663 $ — $ 2,539 (a) Investments measured at net asset value represent certain investments that have been measured at net asset value per share (or its equivalent) and thus are not classified in the fair value hierarchy. In accordance with ASC 820, Fair Value Measurements, the fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the pension assets disclosed in Note 8, Employee Benefit Plans.

Other Comprehensive Income _ (L

Other Comprehensive Income / (Loss)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Other Comprehensive Income / (Loss)	Other Comprehensive Income / (Loss) CSX reports comprehensive earnings or loss in accordance with the Comprehensive Income Topic in the ASC in the Consolidated Comprehensive Income Statement. Total comprehensive earnings are defined as all changes in shareholders' equity during a period, other than those resulting from investments by and distributions to shareholders (e.g. issuance of equity securities and dividends). Generally, for CSX, total comprehensive earnings equal net earnings plus or minus adjustments for pension and other post-retirement liabilities. Total comprehensive earnings represent the activity for a period net of tax and were $5.6 billion , $1.7 billion and $2.0 billion for 2017 , 2016 and 2015 , respectively. While total comprehensive earnings is the activity in a period and is largely driven by net earnings in that period, accumulated other comprehensive income or loss (“AOCI”) represents the cumulative balance of other comprehensive income, net of tax, as of the balance sheet date. For CSX, AOCI is primarily the cumulative balance related to pension and other post-retirement benefit adjustments and CSX's share of AOCI of equity method investees. Changes in the AOCI balance by component are shown in the table below. Amounts reclassified in pension and other post-employment benefits to net earnings relate to the amortization of actuarial losses and are included in labor and fringe on the consolidated income statements. See Note 8. Employee Benefit Plans for further information. Other primarily represents CSX's share of AOCI of equity method investees. Amounts reclassified in other to net earnings are included in materials, supplies and other on the consolidated income statements. Pension and Other Post-Employment Benefits Other Accumulated Other Comprehensive Income (Loss) (Dollars in millions) Balance December 26, 2014 - Net of Tax $ (611 ) $ (55 ) $ (666 ) Other Comprehensive Income(Loss) Loss Before Reclassifications (53 ) (8 ) (61 ) Amounts Reclassified to Net Earnings 71 (2 ) 69 Tax (Expense) Benefit (8 ) 1 (7 ) Total Other Comprehensive (Loss) Income 10 (9 ) 1 Balance December 25, 2015 - Net of Tax (601 ) (64 ) (665 ) Other Comprehensive Income (Loss) Income Before Reclassifications (16 ) 3 (13 ) Amounts Reclassified to Net Earnings 50 1 51 Tax Expense (13 ) — (13 ) Total Other Comprehensive Income 21 4 25 Balance December 30, 2016 - Net of Tax (580 ) (60 ) (640 ) Other Comprehensive Income Income Before Reclassifications 148 13 161 Amounts Reclassified to Net Earnings 56 2 58 Tax Expense (64 ) (1 ) (65 ) Total Other Comprehensive Income 140 14 154 Balance December 31, 2017 - Net of Tax $ (440 ) $ (46 ) $ (486 )

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited) Pursuant to Article 3 of the SEC’s Regulation S-X, the following are selected quarterly financial data: Fiscal Year Ended December 2017 (a) Quarters (Dollars in Millions, Except Per Share Amounts) 1st 2nd 3rd 4th Full Year Revenue $ 2,869 $ 2,933 $ 2,743 $ 2,863 $ 11,408 Operating Income 712 958 876 1,121 3,667 Net Earnings (b) 362 510 459 4,140 5,471 Earnings Per Share, Basic (b) $ 0.39 $ 0.55 $ 0.51 $ 4.63 $ 6.01 Earnings Per Share, Assuming Dilution (b) 0.39 0.55 0.51 4.62 5.99 Fiscal Year Ended December 2016 (a) Revenue $ 2,618 $ 2,704 $ 2,710 $ 3,037 $ 11,069 Operating Income 704 840 841 1,004 3,389 Net Earnings 356 445 455 458 1,714 Earnings Per Share, Basic $ 0.37 $ 0.47 $ 0.48 $ 0.49 $ 1.81 Earnings Per Share, Assuming Dilution 0.37 0.47 0.48 0.49 1.81 (a) Prior to third quarter 2017, CSX followed a 52/53 week fiscal reporting calendar and 2016 included 53 weeks. All 2016 information presented in Results of Operations is on a 53-week basis, under Generally Accepted Accounting Principles ("GAAP"). See Note 1, Nature of Operations and Significant Accounting Policies for details regarding the number of days in each quarterly period presented. (b) These results for fourth quarter and full year 2017 include a $3.6 billion , or $3.91 per share, net tax reform benefit. See further discussion in Note 11, Income Taxes.

Summarized Consolidating Financ

Summarized Consolidating Financial Data	12 Months Ended
	Dec. 31, 2017
Summarized Consolidating Financial Data [Abstract]
Summarized Consolidating Financial Data	Summarized Consolidating Financial Data In 2007, CSXT, a wholly-owned subsidiary of CSX Corporation, sold secured equipment notes maturing in 2023 in a registered public offering. CSX has fully and unconditionally guaranteed the notes. In connection with the notes, the Company is providing the following condensed consolidating financial information in accordance with SEC disclosure requirements. Each entity in the consolidating financial information follows the same accounting policies as described in the consolidated financial statements, except for the use of the equity method of accounting to reflect ownership interests in subsidiaries which are eliminated upon consolidation and the allocation of certain expenses of CSX incurred for the benefit of its subsidiaries. Condensed consolidating financial information for the obligor, CSXT, and parent guarantor, CSX, is shown in the following tables. NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Income Statements (Dollars in Millions) Fiscal Year Ended December 2017 CSX Corporation CSX Transportation Eliminations and Other CSX Consolidated Revenue $ — $ 11,334 $ 74 $ 11,408 Expense (158 ) 8,070 (171 ) 7,741 Operating Income 158 3,264 245 3,667 Equity in Earnings of Subsidiaries 5,810 — (5,810 ) — Interest Expense (582 ) (29 ) 65 (546 ) Other Income - Net 7 42 (28 ) 21 Earnings Before Income Taxes 5,393 3,277 (5,528 ) 3,142 Income Tax Benefit 78 2,247 4 2,329 Net Earnings $ 5,471 $ 5,524 $ (5,524 ) $ 5,471 Total Comprehensive Earnings $ 5,625 $ 5,538 $ (5,538 ) $ 5,625 Fiscal Year Ended December 2016 Revenue $ — $ 10,991 $ 78 $ 11,069 Expense (265 ) 8,100 (155 ) 7,680 Operating Income 265 2,891 233 3,389 Equity in Earnings of Subsidiaries 1,997 2 (1,999 ) — Interest Expense (583 ) (35 ) 39 (579 ) Other Income - Net (112 ) 44 (1 ) (69 ) Earnings Before Income Taxes 1,567 2,902 (1,728 ) 2,741 Income Tax Benefit (Expense) 147 (1,081 ) (93 ) (1,027 ) Net Earnings $ 1,714 $ 1,821 $ (1,821 ) $ 1,714 Total Comprehensive Earnings $ 1,739 $ 1,833 $ (1,833 ) $ 1,739 Fiscal Year Ended December 2015 Revenue $ — $ 11,733 $ 78 $ 11,811 Expense (589 ) 8,922 (106 ) 8,227 Operating Income 589 2,811 184 3,584 Equity in Earnings of Subsidiaries 1,949 — (1,949 ) — Interest Expense (539 ) (33 ) 28 (544 ) Other Income - Net (4 ) 111 (9 ) 98 Earnings Before Income Taxes 1,995 2,889 (1,746 ) 3,138 Income Tax Expense (27 ) (1,083 ) (60 ) (1,170 ) Net Earnings $ 1,968 $ 1,806 $ (1,806 ) $ 1,968 Total Comprehensive Earnings $ 1,969 $ 1,806 $ (1,806 ) $ 1,969 NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Balance Sheets (Dollars in Millions) As of December 31, 2017 CSX Corporation CSX Transportation Eliminations and Other CSX ASSETS Current Assets: Cash and Cash Equivalents $ 274 $ 121 $ 6 $ 401 Short-term Investments — — 18 18 Accounts Receivable - Net (1 ) 301 670 970 Receivable from Affiliates 1,226 3,517 (4,743 ) — Materials and Supplies — 372 — 372 Other Current Assets (1 ) 145 10 154 Total Current Assets 1,498 4,456 (4,039 ) 1,915 Properties 1 41,479 2,844 44,324 Accumulated Depreciation (1 ) (11,017 ) (1,542 ) (12,560 ) Properties - Net — 30,462 1,302 31,764 Investments in Conrail — — 907 907 Affiliates and Other Companies (39 ) 800 18 779 Investment in Consolidated Subsidiaries 29,405 — (29,405 ) — Other Long-term Assets 39 596 (261 ) 374 Total Assets $ 30,903 $ 36,314 $ (31,478 ) $ 35,739 LIABILITIES AND SHAREHOLDERS' EQUITY Current Liabilities: Accounts Payable $ 105 $ 708 $ 34 $ 847 Labor and Fringe Benefits Payable 52 494 56 602 Payable to Affiliates 4,792 552 (5,344 ) — Casualty, Environmental and Other Reserves — 95 13 108 Current Maturities of Long-term Debt — 19 — 19 Income and Other Taxes Payable (326 ) 455 28 157 Other Current Liabilities 5 153 3 161 Total Current Liabilities 4,628 2,476 (5,210 ) 1,894 Casualty, Environmental and Other Reserves — 222 44 266 Long-term Debt 11,056 733 1 11,790 Deferred Income Taxes - Net (130 ) 6,342 206 6,418 Other Long-term Liabilities 644 320 (314 ) 650 Total Liabilities 16,198 10,093 (5,273 ) 21,018 Shareholders' Equity: Common Stock, $1 Par Value 890 181 (181 ) 890 Other Capital 217 5,096 (5,096 ) 217 Retained Earnings 14,084 20,933 (20,933 ) 14,084 Accumulated Other Comprehensive Loss (486 ) (5 ) 5 (486 ) Noncontrolling Minority Interest — 16 — 16 Total Shareholders' Equity 14,705 26,221 (26,205 ) 14,721 Total Liabilities and Shareholders' Equity $ 30,903 $ 36,314 $ (31,478 ) $ 35,739 NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Balance Sheets (Dollars in Millions) As of December 30, 2016 CSX Corporation CSX Transportation Eliminations and Other CSX ASSETS Current Assets Cash and Cash Equivalents $ 305 $ 281 $ 17 $ 603 Short-term Investments 415 — 2 417 Accounts Receivable - Net 2 215 721 938 Receivable from Affiliates 1,157 2,351 (3,508 ) — Materials and Supplies — 407 — 407 Other Current Assets — 106 16 122 Total Current Assets 1,879 3,360 (2,752 ) 2,487 Properties 1 40,518 2,708 43,227 Accumulated Depreciation (1 ) (10,634 ) (1,442 ) (12,077 ) Properties - Net — 29,884 1,266 31,150 Investments in Conrail — — 840 840 Affiliates and Other Companies (39 ) 643 15 619 Investment in Consolidated Subsidiaries 24,179 — (24,179 ) — Other Long-term Assets 2 607 (291 ) 318 Total Assets $ 26,021 $ 34,494 $ (25,101 ) $ 35,414 LIABILITIES AND SHAREHOLDERS' EQUITY Current Liabilities Accounts Payable $ 95 $ 678 $ 33 $ 806 Labor and Fringe Benefits Payable 40 440 65 545 Payable to Affiliates 3,457 500 (3,957 ) — Casualty, Environmental and Other Reserves — 102 13 115 Current Maturities of Long-term Debt 313 19 (1 ) 331 Income and Other Taxes Payable (346 ) 459 16 129 Other Current Liabilities — 112 2 114 Total Current Liabilities 3,559 2,310 (3,829 ) 2,040 Casualty, Environmental and Other Reserves — 208 51 259 Long-term Debt 10,203 759 — 10,962 Deferred Income Taxes - Net (203 ) 9,541 258 9,596 Other Long-term Liabilities 783 410 (330 ) 863 Total Liabilities 14,342 13,228 (3,850 ) 23,720 Shareholders' Equity Common Stock, $1 Par Value 928 181 (181 ) 928 Other Capital 138 5,095 (5,095 ) 138 Retained Earnings 11,253 15,994 (15,994 ) 11,253 Accumulated Other Comprehensive Loss (640 ) (19 ) 19 (640 ) Noncontrolling Minority Interest — 15 — 15 Total Shareholders' Equity 11,679 21,266 (21,251 ) 11,694 Total Liabilities and Shareholders' Equity $ 26,021 $ 34,494 $ (25,101 ) $ 35,414 Certain prior year data has been reclassified to conform to the current presentation. NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Cash Flow Statements (Dollars in Millions) Fiscal Year Ended December 2017 CSX Corporation CSX Transportation Eliminations and Other CSX Operating Activities Net Cash Provided by (Used in) Operating Activities $ 1,719 $ 2,112 $ (359 ) $ 3,472 Investing Activities Property Additions — (1,848 ) (192 ) (2,040 ) Purchases of Short-term Investments (774 ) — (8 ) (782 ) Proceeds from Sales of Short-term Investments 1,190 — 3 1,193 Proceeds from Property Dispositions — 97 — 97 Other Investing Activities (2 ) 94 (55 ) 37 Net Cash Provided by (Used in) Investing Activities 414 (1,657 ) (252 ) (1,495 ) Financing Activities Long-term Debt Issued 850 — — 850 Long-term Debt Repaid (313 ) (20 ) — (333 ) Dividends Paid (708 ) (600 ) 600 (708 ) Shares Repurchased (1,970 ) — — (1,970 ) Other Financing Activities (23 ) 5 — (18 ) Net Cash Provided by (Used in) Financing Activities (2,164 ) (615 ) 600 (2,179 ) Net Decrease in Cash and Cash Equivalents (31 ) (160 ) (11 ) (202 ) Cash and Cash Equivalents at Beginning of Period 305 281 17 603 Cash and Cash Equivalents at End of Period $ 274 $ 121 $ 6 $ 401 NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Cash Flow Statements (Dollars in Millions) Fiscal Year Ended December 2016 CSX Corporation CSX Transportation Eliminations and Other CSX Operating Activities Net Cash Provided by (Used in) Operating Activities $ 453 $ 2,950 $ (362 ) $ 3,041 Investing Activities Property Additions — (2,208 ) (190 ) (2,398 ) Purchases of Short-term Investments (929 ) — — (929 ) Proceeds from Sales of Short-term Investments 1,325 — — 1,325 Proceeds from Property Dispositions — 195 — 195 Other Investing Activities (41 ) 91 (41 ) 9 Net Cash Provided by (Used in) Investing Activities 355 (1,922 ) (231 ) (1,798 ) Financing Activities Long-term Debt Issued 2,200 — — 2,200 Long-term Debt Repaid (1,400 ) (19 ) — (1,419 ) Dividends Paid (680 ) (600 ) 600 (680 ) Shares Repurchased (1,056 ) — — (1,056 ) Other Financing Activities (11 ) (303 ) 1 (313 ) Net Cash Provided by (Used in) Financing Activities (947 ) (922 ) 601 (1,268 ) Net (Decrease) Increase in Cash and Cash Equivalents (139 ) 106 8 (25 ) Cash and Cash Equivalents at Beginning of Period 444 175 9 628 Cash and Cash Equivalents at End of Period $ 305 $ 281 $ 17 $ 603 NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Cash Flow Statements (Dollars in Millions) Fiscal Year Ended December 2015 CSX Corporation CSX Transportation Eliminations and Other CSX Operating Activities Net Cash Provided by (Used in) Operating Activities $ 983 $ 2,974 $ (587 ) $ 3,370 Investing Activities Property Additions — (2,400 ) (162 ) (2,562 ) Purchases of Short-term Investments (1,734 ) — (5 ) (1,739 ) Proceeds from Sales of Short-term Investments 1,175 — 50 1,225 Proceeds from Property Dispositions — 147 — 147 Other Investing Activities (10 ) 132 (85 ) 37 Net Cash Provided by (Used in) Investing Activities (569 ) (2,121 ) (202 ) (2,892 ) Financing Activities Long-term Debt Issued 1,200 — — 1,200 Long-term Debt Repaid (200 ) (29 ) — (229 ) Dividends Paid (686 ) (750 ) 750 (686 ) Shares Repurchased (804 ) — — (804 ) Other Financing Activities 10 1 (11 ) — Net Cash Provided by (Used in) Financing Activities (480 ) (778 ) 739 (519 ) Net (Decrease) Increase in Cash and Cash Equivalents (66 ) 75 (50 ) (41 ) Cash and Cash Equivalents at Beginning of Period 510 100 59 669 Cash and Cash Equivalents at End of Period $ 444 $ 175 $ 9 $ 628

Nature of Operations and Sign25

Nature of Operations and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	In the opinion of management, the accompanying consolidated financial statements contain all normal, recurring adjustments necessary to fairly present the financial position of CSX and its subsidiaries at December 31, 2017 and December 30, 2016 , and the consolidated statements of income, comprehensive income, cash flows and changes in shareholders’ equity for fiscal years 2017 , 2016 and 2015 . In addition, management has evaluated and disclosed all material events occurring subsequent to the date of the financial statements up to the date this annual report is filed on Form 10-K.
Fiscal Year	Through the second quarter 2017, CSX followed a 52/53 week fiscal reporting calendar with the last day of each reporting period ending on a Friday. The 52/53 week calendar allowed for every quarter and year to be of equal duration, 13 weeks and 52 weeks, respectively. To maintain this calendar, every fifth or sixth year, an extra week was added to the fourth quarter and year, making the reporting periods 14 weeks and 53 weeks, respectively. In 2016, the fourth quarter and fiscal year included this extra week. On July 7, 2017, the Board of Directors of CSX approved a change in the fiscal reporting calendar from a 52/53 week year ending on the last Friday of December to a calendar year ending on December 31 each year, effective beginning with fiscal third quarter 2017. Related to the change in the fiscal calendar: • Fiscal year 2017 (December 31, 2016 through December 31, 2017) contained 366 days, and fiscal year 2016 (December 26, 2015 through December 30, 2016) contained 371 days • Fiscal first quarter 2017 (December 31, 2016 through March 31, 2017) contained 91 days, and fiscal first quarter 2016 (December 26, 2015 through March 25, 2016) contained 91 days • Fiscal second quarter 2017 (April 1, 2017 through June 30, 2017) contained 91 days, and fiscal second quarter 2016 (September 24, 2016 through December 30, 2016) contained 91 days • Fiscal third quarter 2017 (July 1, 2017 through September 30, 2017) contained 92 days, and fiscal third quarter 2016 (June 25, 2016 through September 23, 2016) contained 91 days • Fiscal fourth quarter 2017 (October 1, 2017 through December 31, 2017) contained 92 days, and fiscal fourth quarter 2016 (September 24, 2016 through December 30, 2016) contained 98 days This change did not materially impact comparability of the Company’s financial results for fiscal year 2016 and fiscal year 2017. Accordingly, the change to a calendar fiscal year was made on a prospective basis and operating results for prior periods have not been adjusted. The Company is not required to file a transition report because this change is not deemed a change in fiscal year for purposes of reporting subject to Rule 13a-10 or Rule 15d-10 of the Securities Exchange Act of 1934 as the new fiscal year commenced with the end of the prior fiscal year end and within seven days of the prior fiscal year end. Except as otherwise specified, references to full years indicate CSX’s fiscal years ended on December 31, 2017 and December 30, 2016.
Principles of Consolidation	The consolidated financial statements include results of operations of CSX and subsidiaries over which CSX has majority ownership or financial control. All significant intercompany accounts and transactions have been eliminated. Most investments in companies that were not majority-owned were carried at cost (if less than 20% owned and the Company has no significant influence) or were accounted for under the equity method (if the Company has significant influence but does not have control). These investments are reported within Investment in Conrail or Affiliates and Other Companies on the consolidated balance sheets.
Cash and Cash Equivalents	On a daily basis, cash in excess of current operating requirements is invested in various highly liquid investments having a typical maturity date of three months or less at the date of acquisition. These investments are carried at cost, which approximated market value, and are classified as cash equivalents.
Investments	Investments in instruments with original maturities greater than three months that will mature in less than one year are classified as short-term investments. Investments with original maturities of one year or greater are initially classified within other long-term assets, and the classification is re-evaluated at each balance sheet date.
Allowance for Doubtful Accounts	The Company maintains an allowance for doubtful accounts on uncollectible amounts related to freight receivables, government reimbursement receivables, claims for damages and other various receivables. The allowance is based upon the creditworthiness of customers, historical experience, the age of the receivable and current market and economic conditions. Uncollectible amounts are charged against the allowance account.
Materials and Supplies	Materials and supplies in the consolidated balance sheets are carried at average costs and consist primarily of fuel and parts used in the repair and maintenance of CSXT’s freight car and locomotive fleets, equipment and track structure.
Goodwill	Goodwill represents purchase price in excess of fair value and is related to affiliates of CSXT, primarily P&L Transportation, Inc. Goodwill of $63 million is recorded in other long-term assets in the consolidated balance sheets as of December 2017 and December 2016 , respectively.
Revenue and Expense Recognition	The Company recognizes freight revenue using Free-On-Board Origin pursuant to the Revenue Recognition Topic in the Accounting Standards Codification ("ASC"). Accounting guidance in this topic provides for the allocation of revenue between reporting periods based on relative transit time in each reporting period. Expenses are recognized as incurred. The certain key estimates included in the recognition and measurement of revenue and related accounts receivable under the policies described above are as follows: • revenue associated with shipments in transit is recognized ratably over transit time and is based on average cycle times to move commodities and products from their origin to their final destination or interchange; • adjustments to revenue for billing corrections, billing discounts and bad debts or to accounts receivable for allowances for doubtful accounts; • adjustments to revenue for overcharge claims filed by customers, which are based on historical cash paid to customers for rate overcharges as a percentage of total billing; • incentive-based refunds to customers, which are primarily based on customers achieving certain volume thresholds, are recorded as a reduction to revenue on the basis of management’s best estimate of the projected liability (this estimate is based on historical activity, current volume levels and forecasted future volume). NOTE 1. Nature of Operations and Significant Accounting Policies, continued The Company regularly updates the estimates described above based on historical experience and current conditions. All other revenue, such as demurrage, switching and other incidental charges are recorded upon completion of the service.
New Accounting Pronouncements	In May 2017, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") Compensation - Stock Compensation: Scope of Modification Accounting, which provides clarity on what changes to share-based awards are considered substantive and require modification accounting to be applied. This update is required beginning with first quarter 2018 and should be applied prospectively to award modifications after the effective date. The Company early adopted this standard update in second quarter 2017 and will apply it prospectively to any award modifications after the adoption date. The Company does not regularly modify the terms and conditions of share-based awards and does not believe this standard update will have a material effect on its financial condition, results of operations or liquidity. In March 2017, the FASB issued ASU Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost , which requires that only the service cost component of net periodic benefit costs be recorded as compensation cost in the operating expense section of the income statement. All other components of net periodic benefit cost (interest cost, expected return on plan assets and amortization of net loss) will be presented in other income - net. This standard update is effective beginning with the first quarter 2018 and must be applied retrospectively. The Company does not believe this standard update will have a material effect on its financial condition, results of operations or liquidity. The Company currently records service costs and net benefit costs within labor and fringe expense. In 2017, pension and other post-retirement benefit charges and pension settlement charges totaling $85 million were included in the restructuring charge. Beginning in first quarter 2018, only the service cost will be recorded within labor and fringe expense, and the other components of net benefit costs will be recorded in other income. The retrospective impact of adoption will be an increase in operating income for the prior years presented as the other components were a net expense. The impact of adoption is projected to be a decrease in operating income for 2018. The retrospective impact of adoption is shown in the following table. Fiscal Years 2017 2016 2015 Increase in Operating Income $ 53 $ 24 $ 44 Decrease in Other Income (53 ) (24 ) (44 ) In March 2017, the FASB issued ASU Simplifying the Test for Goodwill Impairment, which eliminates step two, the calculation of the implied fair value of goodwill, from the goodwill impairment test. Impairment will be quantified in step one of the test as the amount by which the carrying amount exceeds the fair value. This standard update is effective beginning first quarter 2020 and must be applied prospectively. The Company does not believe this standard update will have a material effect on its financial condition, results of operations or liquidity. NOTE 1. Nature of Operations and Significant Accounting Policies, continued In May 2014, the FASB issued ASU Revenue from Contracts with Customers , which supersedes previous revenue recognition guidance. The new standard requires that a company recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration the company expects to receive in exchange for those goods or services. Companies will need to use more judgment and estimates than under the guidance currently in effect, including estimating the amount of variable revenue to recognize over each identified performance obligation. Additional disclosures will be required to help users of financial statements understand the nature, amount and timing of revenue and cash flows arising from contracts. CSX will adopt this standard update in first quarter 2018 using a modified retrospective method of adoption. The FASB has also issued several amendments to the revenue standard, including clarification on accounting for principal versus agent considerations (i.e., reporting gross versus net), licenses of intellectual property and identifying performance obligations. These amendments do not change the core principle of the standard, but provide clarity and implementation guidance. The Company is currently finalizing its review of the impact of adopting this new guidance and has developed a comprehensive implementation plan. In-depth reviews of commercial contracts have been completed and changes to processes and internal controls to meet the standard’s reporting and disclosure requirements have been identified and are being implemented. Adoption of this standard update will not materially impact the Company's financial condition, results of operations or liquidity. Freight revenue will continue to be recognized ratably over transit time. Additionally, the disaggregated revenue information required to be disclosed under this standard update is similar to the information currently included in the Results of Operations section of Item 2, “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” In February 2016, the FASB issued ASU, Leases , which will require lessees to recognize most leases on their balance sheets as a right-of-use asset with a corresponding lease liability, and lessors to recognize a net lease investment. Additional qualitative and quantitative disclosures will also be required. This standard update is effective for CSX beginning with the first quarter 2019 and will be adopted using a modified retrospective method. Changes to processes and internal controls to meet the standard’s reporting and disclosure requirements have been identified and are being implemented. Software has been implemented that will assist in the recognition of additional assets and liabilities to be included on the balance sheet related to leases currently classified as operating leases with durations greater than twelve months, with certain allowable exceptions. The Company continues to evaluate the expected impact of this standard update on disclosures, but does not anticipate any material changes to operating results or liquidity.
Use of Estimates	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires that management make estimates in reporting the amounts of certain assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of certain revenues and expenses during the reporting period. Actual results may differ from those estimates. Critical accounting estimates using management judgment are made for the following areas: • personal injury, environmental and legal reserves (see Note 5, Casualty, Environmental and Other Reserves ); • pension and post-retirement medical plan accounting (see Note 8, Employee Benefit Plans ); • depreciation policies for assets under the group-life method (see Note 6, Properties ); and • income taxes (see Note 11, Income Taxes ).
Earnings Per Share	Basic earnings per share is based on the weighted-average number of shares of common stock outstanding. Earnings per share, assuming dilution, is based on the weighted-average number of shares of common stock equivalents outstanding adjusted for the effects of common stock that may be issued as a result of potentially dilutive instruments. CSX's potentially dilutive instruments are made up of equity awards, which include long-term incentive awards and employee stock options. The Earnings Per Share Topic in the ASC requires CSX to include additional shares in the computation of earnings per share, assuming dilution. The additional shares included in diluted earnings per share represent the number of shares that would be issued if all of the above potentially dilutive instruments were converted into CSX common stock. When calculating diluted earnings per share, CSX is required to include the potential shares that would be outstanding if all outstanding stock options were exercised. This number is different from outstanding stock options, which is included in Note 4, Stock Plans and Share-Based Compensation , because it is offset by shares CSX could repurchase using the proceeds from these hypothetical exercises to obtain the common stock equivalent. Approximately 7.6 million , 2.8 million and 2.5 million of total average outstanding stock options for 2017, 2016 and 2015, respectively, were excluded from the diluted earnings per share calculation because their effect was antidilutive.
Casualty Reserves	In accordance with the Contingencies Topic in the ASC, to the extent the value of an individual claim exceeds the self-insured retention amount, the Company would present the liability on a gross basis with a corresponding receivable for insurance recoveries. These reserves fluctuate based upon the timing of payments as well as changes in estimate. Actual results may vary from estimates due to the number, type and severity of the injury, costs of medical treatments and uncertainties in litigation. Most of the Company's casualty claims relate to CSXT unless otherwise noted below. Defense and processing costs, which historically have been insignificant and are anticipated to be insignificant in the future, are not included in the recorded liabilities.
Environmental	Environmental reserves were $90 million and $95 million for 2017 and 2016 , respectively. The Company is a party to various proceedings related to environmental issues, including administrative and judicial proceedings involving private parties and regulatory agencies. The Company has been identified as a potentially responsible party at approximately 214 environmentally impaired sites. Many of these are, or may be, subject to remedial action under the federal Comprehensive Environmental Response, Compensation and Liability Act of 1980 ("CERCLA"), also known as the Superfund Law, or similar state statutes. Most of these proceedings arose from environmental conditions on properties used for ongoing or discontinued railroad operations. A number of these proceedings, however, are based on allegations that the Company, or its predecessors, sent hazardous substances to facilities owned or operated by others for treatment, recycling or disposal. In addition, some of the Company’s land holdings were leased to others for commercial or industrial uses that may have resulted in releases of hazardous substances or other regulated materials onto the property and could give rise to proceedings against the Company. In any such proceedings, the Company is subject to environmental clean-up and enforcement actions under the Superfund Law, as well as similar state laws that may impose joint and several liability for clean-up and enforcement costs on current and former owners and operators of a site without regard to fault or the legality of the original conduct. These costs could be substantial. NOTE 5. Casualty, Environmental and Other Reserves, continued In accordance with the Asset Retirement and Environmental Obligations Topic in the ASC, the Company reviews its role with respect to each site identified at least quarterly, giving consideration to a number of factors such as: • type of clean-up required; • nature of the Company’s alleged connection to the location (e.g., generator of waste sent to the site or owner or operator of the site); • extent of the Company’s alleged connection (e.g., volume of waste sent to the location and other relevant factors); and • number, connection and financial viability of other named and unnamed potentially responsible parties at the location. Based on the review process, the Company has recorded amounts to cover contingent anticipated future environmental remediation costs with respect to each site to the extent such costs are reasonably estimable and probable. The recorded liabilities for estimated future environmental costs are undiscounted. The liability includes future costs for remediation and restoration of sites as well as any significant ongoing monitoring costs, but excludes any anticipated insurance recoveries. Payments related to these liabilities are expected to be made over the next several years. Environmental remediation costs are included in materials, supplies and other on the consolidated income statements. Currently, the Company does not possess sufficient information to reasonably estimate the amounts of additional liabilities, if any, on some sites until completion of future environmental studies. In addition, conditions that are currently unknown could, at any given location, result in additional exposure, the amount and materiality of which cannot presently be reasonably estimated. Based upon information currently available, however, the Company believes its environmental reserves accurately reflect the estimated cost of remedial actions currently required.
Depreciation Method	The depreciable assets of the Company are depreciated using either the group-life or straight-line method of accounting, which are both acceptable depreciation methods in accordance with GAAP. The Company depreciates its railroad assets, including main-line track, locomotives and freight cars, using the group-life method. Assets depreciated under the group-life method comprise 86% of total fixed assets of $44 billion on a gross basis as of December 2017. The remaining depreciable assets of the Company, including non-railroad assets and assets under capital leases, are depreciated using the straight-line method on a per asset basis. Land is not depreciated. The group-life method aggregates assets with similar lives and characteristics into groups and depreciates each of these groups as a whole. When using the group-life method, an underlying assumption is that each group of assets, as a whole, is used and depreciated to the end of its group’s recoverable life. The Company currently utilizes different depreciable asset categories to account for depreciation expense for the railroad assets that are depreciated under the group-life method. By utilizing various depreciable categories, the Company can more accurately account for the use of its assets. All assets of the Company are depreciated on a time or life basis. The group-life method of depreciation closely approximates the straight-line method of depreciation. Additionally, due to the nature of most of its assets (e.g. track is one contiguous, connected asset), the Company believes that this is the most effective way to properly depreciate its assets. Estimated Useful Life Management performs a review of depreciation expense and useful lives on a regular basis. Under the group-life method, the service lives and salvage values for each group of assets are determined by completing periodic depreciation studies and applying management’s assumptions regarding the service lives of its properties. A depreciation study is the periodic review of asset service lives, salvage values, accumulated depreciation, and other related factors for group assets conducted by a third-party specialist, analyzed by the Company’s management and approved by the STB, the regulatory board that has broad jurisdiction over railroad practices. The STB requires depreciation studies be performed every three years for equipment assets (e.g. locomotives and freight cars) and every six years for road and track assets (e.g. bridges, signals, rail, ties, and ballast). The Company believes the frequency currently required by the STB provides adequate review of asset service lives and that a more frequent review would not result in a material change due to the long-lived nature of most of the assets. In 2016, the Company completed a depreciation study for its equipment assets. The Company plans to complete the next depreciation study for equipment assets in 2019 and road and track assets in 2020.
Impairment Review	Properties and other long-lived assets are reviewed for impairment whenever events or business conditions indicate the carrying amount of such assets may not be fully recoverable. Initial assessments of recoverability are based on estimates of undiscounted future net cash flows associated with an asset or a group of assets in accordance with the Property, Plant, and Equipment Topic in the ASC. Where impairment is indicated, the assets are evaluated and their carrying amount is reduced to fair value based on discounted net cash flows or other estimates of fair value.

Nature of Operations and Sign26

Nature of Operations and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Retrospective Impact of Future Adoption	The retrospective impact of adoption will be an increase in operating income for the prior years presented as the other components were a net expense. The impact of adoption is projected to be a decrease in operating income for 2018. The retrospective impact of adoption is shown in the following table. Fiscal Years 2017 2016 2015 Increase in Operating Income $ 53 $ 24 $ 44 Decrease in Other Income (53 ) (24 ) (44 )
Restructuring Charges	Expenses related to the management workforce reduction and other costs are shown in the following table. 2017 (Dollars in millions) First Quarter Second Quarter Third Quarter Fourth Quarter Year-to-Date Severance $ 81 $ 10 $ — $ 7 $ 98 Pension and Other Post-Retirement Benefit Charges 63 7 — 3 73 Share-Based Compensation Remeasurement 5 3 — 7 15 Relocation 6 2 — — 8 Subtotal Management Workforce Reduction $ 155 $ 22 $ — $ 17 $ 194 Reimbursement Arrangements — 84 — — 84 Non-Cash Executive Equity Awards Proration 8 16 — — 24 Non-Cash Pension Settlement Charge — — — 12 12 Other Charges Including Fees Related to Shareholder Matters 10 — 1 — 11 Total Restructuring Charge $ 173 $ 122 $ 1 $ 29 $ 325 NOTE 1. Nature of Operations and Significant Accounting Policies, continued Charges and payments related to the management workforce reduction and other costs are shown in the following table. (Dollars in millions) 2017 Charges 2017 Payments Non-cash Items Liability 12/31/2017 Severance $ 98 $ (86 ) $ — $ 12 Pension, Other Post-Retirement Benefit Charges (a) 73 — (73 ) — Share-Based Compensation Remeasurement 15 — (15 ) — Relocation 8 (6 ) — 2 Subtotal Management Workforce Reduction $ 194 $ (92 ) $ (88 ) $ 14 Reimbursement Arrangements 84 (84 ) — — Non-Cash Executive Equity Awards Proration 24 — (24 ) — Non-Cash Pension Settlement Charge 12 — (12 ) — Other Charges Including Fees Related to Shareholder Matters 11 (11 ) — — Total Restructuring Charge $ 325 $ (187 ) $ (124 ) $ 14 (a) The majority of non-cash items are related to certain benefits paid through CSX's qualified pension plans.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings per Share	The following table sets forth the computation of basic earnings per share and earnings per share, assuming dilution: Fiscal Years 2017 2016 2015 Numerator (Dollars in Millions) : Net Earnings $ 5,471 $ 1,714 $ 1,968 Dividend Equivalents on Restricted Stock (1 ) (1 ) (1 ) Net Earnings, Attributable to Common Shareholders $ 5,470 $ 1,713 $ 1,967 Denominator (Units in Millions) : Average Common Shares Outstanding 911 947 983 Other Potentially Dilutive Common Shares 3 1 1 Average Common Shares Outstanding, Assuming Dilution 914 948 984 Net Earnings Per Share, Basic $ 6.01 $ 1.81 $ 2.00 Net Earnings Per Share, Assuming Dilution $ 5.99 $ 1.81 $ 2.00
Schedule of Share Repurchases	During 2017, 2016, and 2015, CSX repurchased the following shares: Fiscal Years 2017 2016 2015 Shares Repurchased (Units in Millions) 39 38 26 Cost of Shares (Dollars in Millions) $ 1,970 $ 1,056 $ 804

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Schedule of Common and Preferred Stock	Common and preferred stock consists of the following: Common Stock, $1 Par Value December 2017 (Units in Millions) Common Shares Authorized 1,800 Common Shares Issued and Outstanding 890 Preferred Stock Preferred Shares Authorized 25 Preferred Shares Issued and Outstanding —

Stock Plans and Share-Based C29

Stock Plans and Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-Based Compensation and Related Income Tax Benefit	The year over year increase in expense related to performance units and stock options is primarily due to modifications to the terms of awards (see Equity Award Modifications below) and higher expected award payouts. Fiscal Years (Dollars in Millions) 2017 2016 2015 Share-Based Compensation Expense Performance Units $ 49 $ 17 $ (1 ) Restricted Stock Units and Awards 15 11 11 Stock Options 22 7 — Stock Awards for Directors 3 2 2 Total Share-based Compensation Expense $ 89 $ 37 $ 12 Income Tax Benefit $ 34 $ 14 $ 4
Summary of Performance Unit Grant and Vesting Information	Performance unit grant and vesting information is summarized as follows: Fiscal Years 2017 2016 2015 Weighted-average grant date fair value $ 49.50 $ 24.17 $ 35.45 Fair value of units vested in fiscal year ending (in millions) $ 26 $ 31 $ 34
Performance Unit Activity Related to Outstanding Long-term Incentive Plans and Corresponding Fair Value	The performance unit activity related to the outstanding long-term incentive plans and corresponding fair value is summarized as follows: Performance Units Outstanding Weighted-Average Fair Value at Grant Date Unvested at December 30, 2016 1,581 $ 30.00 Granted 644 49.50 Forfeited (530 ) 38.47 Vested (719 ) 35.94 Unvested at December 31, 2017 976 $ 33.90
Summary of Restricted Stock Grant and Vesting Information	Restricted stock grant and vesting information is summarized as follows: Fiscal Years 2017 2016 2015 Weighted-average grant date fair value $ 48.35 $ 24.21 $ 35.94 Fair value of units and awards vested during fiscal year ended (in millions) $ 8 $ 14 $ 9
Schedule of Outstanding Restricted Stock Units and Awards	The restricted stock activity related to the outstanding long-term incentive plans and corresponding fair value is summarized as follows: Restricted Stock Units and Awards Outstanding Weighted-Average Fair Value at Grant Date Unvested at December 30, 2016 1,076 $ 28.19 Granted 328 48.35 Forfeited (297 ) 36.48 Vested (300 ) 28.09 Unvested at December 31, 2017 807 $ 33.37
Summary of Assumptions and Inputs Used to Estimate Fair Value of Stock Options	Assumptions and inputs used to estimate fair value of stock options are summarized as follows: Fiscal Years 2017 2016 2015 Weighted-average grant date fair value $ 12.84 $ 4.68 $ 5.31 Stock options valuation assumptions: Annual dividend yield 1.5 % 3 % 3 % Risk-free interest rate 2.2 % 1 % 2 % Annualized volatility 27.1 % 27 % 28 % Expected life (in years) 6.3 6.5 6.5 Other pricing model inputs: Weighted-average grant-date market price of CSX stock (strike price) $ 49.63 $ 24.13 $ 24.99
Summary of Stock Option Activity	The stock option activity is summarized as follows: Stock Options Outstanding Weighted-Average Exercise Price Outstanding at December 30, 2016 4,582 $ 24.57 Granted 10,462 49.63 Forfeited (10,860 ) 46.81 Exercised 22 25.18 Outstanding at December 31, 2017 4,163 $ 29.52 Exercisable at December 31, 2017 — —

Casualty, Environmental and O30

Casualty, Environmental and Other Reserves (Tables)	12 Months Ended
	Dec. 31, 2017
Casualty, Environmental and Other Reserves [Abstract]
Schedule of Claims Activity	Activity related to casualty, environmental and other reserves is as follows: Casualty Environmental Other (Dollars in Millions) Reserves Reserves Reserves Total December 26, 2014 $ 265 $ 94 $ 59 $ 418 Charged to Expense 60 45 37 142 Payments (56 ) (57 ) (47 ) (160 ) December 25, 2015 269 82 49 400 Charged to Expense 52 46 30 128 Change in Estimate (a) (28 ) — — (28 ) Payments (64 ) (33 ) (29 ) (126 ) December 30, 2016 229 95 50 374 Charged to Expense 43 26 45 114 Payments (44 ) (31 ) (39 ) (114 ) December 31, 2017 $ 228 $ 90 $ 56 $ 374 (a) Changes in estimates are the result of continued safety improvements and a continuing decline in the severity of injuries.
Casualty, Environmental and Other Reserves	Casualty, environmental and other reserves are provided for in the consolidated balance sheets as shown in the table below. December 2017 December 2016 (Dollars in Millions) Current Long-term Total Current Long-term Total Casualty: Personal Injury $ 43 $ 125 $ 168 $ 46 $ 124 $ 170 Occupational 6 54 60 7 52 59 Total Casualty $ 49 $ 179 $ 228 $ 53 $ 176 $ 229 Environmental 31 59 90 42 53 95 Other 28 28 56 20 30 50 Total $ 108 $ 266 $ 374 $ 115 $ 259 $ 374

Properties (Tables)

Properties (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of Net Properties	A detail of the Company’s net properties are as follows: (Dollars in Millions) Accumulated Net Book Annual Depreciation Estimated Useful Life Depreciation December 2017 Cost Depreciation Value Rate ( Avg. Years) Method (a) Road Rail and Other Track Material $ 7,694 $ (1,606 ) $ 6,088 2.5% 40 Group Life Ties 5,665 (1,446 ) 4,219 3.7% 27 Group Life Grading 2,662 (542 ) 2,120 1.4% 90 Group Life Ballast 2,994 (921 ) 2,073 2.7% 37 Group Life Bridges, Trestles, and Culverts 2,405 (356 ) 2,049 1.6% 70 Group Life Signals and Interlockers 2,759 (588 ) 2,171 4.0% 25 Group Life/ Straight Line Buildings 1,278 (464 ) 814 2.5% 40 Group Life Other 4,634 (1,867 ) 2,767 4.2% 24 Group Life Total Road 30,091 (7,790 ) 22,301 Equipment Locomotive 6,083 (2,490 ) 3,593 3.5% 29 Group Life Freight Cars 3,262 (998 ) 2,264 2.9% 35 Group Life Work Equipment and Other 2,261 (1,282 ) 979 7.4% 14 Group Life/ Straight Line Total Equipment 11,606 (4,770 ) 6,836 Land 1,849 — 1,849 N/A N/A N/A Construction In Progress 778 — 778 N/A N/A N/A Total Properties $ 44,324 $ (12,560 ) $ 31,764 (a) For depreciation method, certain asset categories contain intermodal terminals or technology-related assets, which are depreciated using the straight-line method. NOTE 6. Properties, continued (Dollars in Millions) Accumulated Net Book Annual Depreciation Estimated Useful Life Depreciation December 2016 Cost Depreciation Value Rate (Avg. Years) Method (a) Road Rail and Other Track Material $ 7,326 $ (1,493 ) $ 5,833 2.5% 40 Group Life Ties 5,368 (1,292 ) 4,076 3.7% 27 Group Life Grading 2,600 (514 ) 2,086 1.4% 90 Group Life Ballast 2,897 (860 ) 2,037 2.7% 37 Group Life Bridges, Trestles, and Culverts 2,306 (317 ) 1,989 1.6% 70 Group Life Signals and Interlockers 2,523 (496 ) 2,027 4.0% 25 Group Life/ Straight Line Buildings 1,238 (447 ) 791 2.5% 40 Group Life Other 4,566 (1,905 ) 2,661 4.2% 24 Group Life Total Road 28,824 (7,324 ) 21,500 Equipment Locomotive 6,110 (2,504 ) 3,606 3.5% 29 Group Life Freight Cars 3,386 (1,046 ) 2,340 2.9% 35 Group Life Work Equipment and Other 2,108 (1,190 ) 918 7.4% 14 Group Life/ Straight Line Total Equipment 11,604 (4,740 ) 6,864 Land 1,833 — 1,833 N/A N/A N/A Construction In Progress 913 — 913 N/A N/A N/A Other 53 (13 ) 40 N/A 32 Straight Line Total Properties $ 43,227 $ (12,077 ) $ 31,150 (a) For depreciation method, certain asset categories contain intermodal terminals or technology-related assets, which are depreciated using the straight-line method.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Rent Expense Associated with Operating Leases	Rent expense on operating leases is included in equipment and other rents on the consolidated income statements. The Company uses the straight-line method to recognize rent expense on operating leases that include escalations over their terms. These amounts are shown in the table below. Fiscal Years (Dollars in Millions) 2017 2016 2015 Rent Expense on Operating Leases (a) $ 78 $ 77 $ 86 (a) Prior year data has been reclassified to conform to the current presentation.
Schedule of Minimum Rentals and Commitments under Operating Leases	At December 2017 , minimum rentals on land, buildings, track and equipment under operating leases are disclosed in the table below. Also, payments to Conrail for leases on shared rail infrastructure are included in these amounts. (See Note 12, Related Party Transactions ). (Dollars in Millions) Operating Sublease Net Lease Years Leases Income Commitments 2018 $ 68 $ (3 ) $ 65 2019 64 (3 ) 61 2020 50 (3 ) 47 2021 45 (3 ) 42 2022 41 (3 ) 38 Thereafter 128 (6 ) 122 Total $ 396 $ (21 ) $ 375
Schedule of Number of Locomotives and Payments under Long-term Maintenance Program	The following table summarizes the number of locomotives covered and CSXT’s payments under the long-term maintenance program. Fiscal Years (Dollars in Millions) 2017 2016 2015 Amounts Paid $ 197 $ 230 $ 233 Number of Locomotives 2,062 2,243 2,310
Schedule of Annual Payments under Long-term Maintenance Program	Total annual payments under all of these purchase commitments are also estimated in the table below. (Dollars in Millions) Locomotive Maintenance Payments Other Commitments Total 2018 $ 171 $ 119 $ 290 2019 162 67 229 2020 218 35 253 2021 223 35 258 2022 225 33 258 Thereafter 2,716 213 2,929 Total $ 3,715 $ 502 $ 4,217

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Summary of Participants	In order to perform this valuation, the actuaries are provided with the details of the population covered at the beginning of the year, summarized in the table below, and projects that population forward to the end of the year . Summary of Participants as of January 1, 2017 Pension Plans Post-retirement Medical Plan Active Employees 3,744 458 Retirees and Beneficiaries 12,723 9,940 Other (a) 3,591 36 Total 20,058 10,434 (a) For pension plans, the other category consists mostly of terminated but vested former employees. For post-retirement plans, the other category consists of employees on long-term disability that have not yet retired.
Schedule of Future Expected Benefit Payments	Future expected benefit payments are as follows: Expected Cash Flows (Dollars in Millions) Pension Benefits Post-retirement Benefits 2018 $ 198 $ 38 2019 193 28 2020 189 26 2021 186 24 2022 183 22 2023-2026 888 76 Total $ 1,837 $ 214
Schedule of Allocation of Plan Assets	The distribution of pension plan assets as of the measurement date is shown in the table below, and these assets are reported net of pension liabilities on the balance sheet. December 2017 December 2016 Percent of Percent of (Dollars in Millions) Amount Total Assets Amount Total Assets Equity $ 2,060 73 % $ 1,806 71 % Fixed Income 729 26 665 26 Cash and Cash Equivalents 44 1 68 3 Total $ 2,833 100 % $ 2,539 100 %
Schedule of Changes in Benefit Obligation and Fair Value of Plan Assets	Changes in benefit obligation and the fair value of plan assets for the 2017 and 2016 calendar plan years are as follows: Pension Benefits Post-retirement Benefits Plan Year Plan Year Plan Year Plan Year (Dollars in Millions) 2017 2016 2017 2016 Actuarial Present Value of Benefit Obligation Accumulated Benefit Obligation $ 2,873 $ 2,717 N/A N/A Projected Benefit Obligation 3,002 2,871 $ 250 $ 274 Change in Projected Benefit Obligation: Projected Benefit Obligation at Beginning of Plan Year $ 2,871 $ 2,860 $ 274 $ 314 Service Cost 36 48 2 2 Interest Cost 92 119 7 12 Plan Participants' Contributions — — 7 6 Workforce Reduction Program/Curtailment 58 — 13 — Actuarial Loss (Gain) 163 20 (17 ) (22 ) Benefits Paid (218 ) (176 ) (36 ) (38 ) Benefit Obligation at End of Plan Year $ 3,002 $ 2,871 $ 250 $ 274 Change in Plan Assets: Fair Value of Plan Assets at Beginning of Plan Year $ 2,539 $ 2,309 $ — $ — Actual Return on Plan Assets 467 139 — — Qualified Employer Contributions — 250 — — Non-qualified Employer Contributions 45 17 29 32 Plan Participants' Contributions — — 7 6 Benefits Paid (218 ) (176 ) (36 ) (38 ) Fair Value of Plan Assets at End of Plan Year 2,833 2,539 — — Funded Status at End of Plan Year $ (169 ) $ (332 ) $ (250 ) $ (274 )
Schedule of Amount Recognized in Balance Sheet	Amounts related to pension and post-retirement benefits recorded in other long-term assets, labor and fringe benefits payable and other long-term liabilities on the balance sheet are as follows: Pension Benefits Post-retirement Benefits December December December December (Dollars in Millions) 2017 2016 2017 2016 Amounts Recorded in Consolidated Balance Sheets: Long-term Assets (a) $ 57 $ 9 $ — $ — Current Liabilities (15 ) (15 ) (38 ) (39 ) Long-term Liabilities (211 ) (326 ) (212 ) (235 ) Net Amount Recognized in Consolidated Balance Sheets $ (169 ) $ (332 ) $ (250 ) $ (274 ) (a) Long-term assets as of December 2017 and 2016 relate to qualified pension plans where assets exceed projected benefit obligations.
Benefit Obligations in Excess of Plan Assets	At December 2017 , benefit obligations of the unfunded CSX non-qualified pension plans is disclosed below. Aggregate (Dollars in Millions) Fair Value Aggregate Benefit Obligations in Excess of Plan Assets of Plan Assets Benefit Obligation Projected Benefit Obligation $ — $ (226 ) Accumulated Benefit Obligation — (216 )
Schedule of Net Benefit Expense	The following table describes the components of expense/(income) related to net benefit expense recorded in labor and fringe on the income statement. Pension Benefits Fiscal Years Post-retirement Benefits Fiscal Years (Dollars in Millions) 2017 2016 2015 2017 2016 2015 Service Cost $ 36 $ 48 $ 45 $ 2 $ 2 $ 2 Interest Cost 92 119 116 7 12 12 Expected Return on Plan Assets (171 ) (157 ) (162 ) — — — Amortization of Net Loss 41 48 70 — 3 4 Amortization of Prior Service Cost — — — — — (1 ) Net Periodic Benefit Expense (2 ) 58 69 9 17 17 Special Termination Benefits - Workforce Reduction Program/Curtailment 60 — 7 13 — — Settlement Loss (Gain) 11 (1 ) (2 ) — — — Total Expense $ 69 $ 57 $ 74 $ 22 $ 17 $ 17
Schedule of Pre-tax Change in Other Comprehensive Loss (Income)	The following table shows the pre-tax change in other comprehensive loss (income) attributable to the components of net expense and the change in benefit obligation for CSX for pension and other post-employment benefits. (Dollars in Millions) Pension Benefits Post-retirement Benefits Components of Other Comprehensive December December December December Loss (Income) 2017 2016 2017 2016 Recognized in the balance sheet (Gains) Losses $ (131 ) $ 38 $ (17 ) $ (22 ) Expense (Income) recognized in the income statement Amortization of net losses (a) $ 41 $ 48 $ — $ 3 Settlement gain 11 (1 ) — — Curtailment loss 4 — — — (a) Amortization of net losses estimated to be expensed for 2018 is approximately $43 million for pension benefits.
Schedule of Pre-tax Amounts to be Amortized that are Included in Accumulated Other Comprehensive Loss	As of December 2017 , the balances of pre-tax losses to be amortized related to the Company's pension and post-retirement obligations are $705 million and $7 million , respectively. These amounts are included in accumulated other comprehensive loss, a component of shareholders’ equity.
Schedule of Weighted-Average Assumptions Used	The weighted averages of assumptions used by the Company to value its pension and post-retirement obligations were as follows: Pension Benefits Post-retirement Benefits 2017 2016 2017 2016 Expected Long-term Return on Plan Assets: Benefit Cost for Current Plan Year 6.75 % 7.00 % N/A N/A Benefit Cost for Subsequent Plan Year 6.75 % 6.75 % N/A N/A Discount Rates: Benefit Cost for Plan Year — % — % — % — % Service Cost for Plan Year 4.26 % (a) 4.30 % 4.11 % (b) 3.85 % Interest Cost for Plan Year 3.26 % (a) 4.30 % 2.78 % (b) 3.85 % Benefit Obligation at End of Plan Year 3.56 % 4.08 % 3.34 % 3.71 % Salary Scale Inflation 4.60 % 4.60 % N/A N/A (a) The pension benefits service cost and interest cost for 2017 were based on a weighted average discount rate of 4.35% and 3.37% , respectively, prior to the management workforce reduction program initiated in 2017 and were reduced to 4.26% and 3.26% , respectively, after the Company remeasured the pension benefits obligation and pension plan assets in the second quarter of 2017. (b) The post-retirement benefits service cost and interest cost for 2017 were based on a weighted average discount rate of 4.20% and 2.88% , respectively, prior to the management workforce reduction program initiated in 2017 and were reduced to 4.11% and 2.78% , respectively, after the Company remeasured the other post-retirement benefits obligation in the first quarter of 2017.

Debt and Credit Agreements (Tab

Debt and Credit Agreements (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Debt at December 2017 and December 2016 is shown in the table below. For information regarding the fair value of debt, see Note 13, Fair Value Measurements. Maturity at December Average Interest Rates at December December December (Dollars in Millions) 2017 2017 2017 2016 Notes 2020-2066 4.3% $ 11,591 $ 11,055 Equipment Obligations (a) 2018-2023 6.3% 213 232 Capital Leases 2018-2026 16.2% 5 6 Subtotal Long-term Debt (including current portion) $ 11,809 $ 11,293 Less Debt Due within One Year (19 ) (331 ) Long-term Debt (excluding current portion) $ 11,790 $ 10,962 (a) Equipment obligations are secured by an interest in certain railroad equipment.
Schedule of Long-term Debt Maturities	Long-term Debt Maturities (Net of Discounts, Premiums and Issuance Costs) (Dollars in Millions) Maturities as of Fiscal Years Ending December 2017 2018 $ 19 2019 18 2020 745 2021 371 2022 162 Thereafter 10,494 Total Long-term Debt Maturities, including current portion $ 11,809

Other Income - Net (Tables)

Other Income - Net (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Schedule of Other Income - Net	Other income – net consisted of the following: Fiscal Years (Dollars in Millions) 2017 2016 2015 Interest Income $ 13 $ 10 $ 6 Income from Non-operating Real Estate Activities — 27 83 Miscellaneous Income (Expense) 8 9 9 Total Other Income (Expense) - Net $ 21 $ 46 $ 98 Gross Revenue from Real Estate Operations included above $ — $ 56 $ 104

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Breakdown of Income Tax Expense Between Current and Deferred	The breakdown of income tax expense between current and deferred is as follows: Fiscal Years (Dollars in Millions) 2017 2016 2015 Current: Federal $ 787 $ 540 $ 619 State 117 82 95 Subtotal Current 904 622 714 Deferred: Federal (3,277 ) 355 414 State 44 50 42 Subtotal Deferred (3,233 ) 405 456 Total $ (2,329 ) $ 1,027 $ 1,170
Schedule of Income Tax Expense Reconciled to Tax Computed at Statutory Rates	Fiscal Years (Dollars In Millions) 2017 2016 2015 Federal Income Taxes $ 1,100 35.0 % $ 959 35.0 % $ 1,098 35.0 % State Income Taxes 102 3.2 % 83 3.0 % 86 2.7 % Deferred Tax Rate Change (3,506 ) (111.6 )% — — % — — % Other (25 ) (0.8 )% (15 ) (0.5 )% (14 ) (0.4 )% Income Tax (Benefit) Expense/Rate $ (2,329 ) (74.2 )% $ 1,027 37.5 % $ 1,170 37.3 %
Schedule of Significant Components of Deferred Income Tax Assets and Liabilities	The significant components of deferred income tax assets and liabilities include: 2017 2016 (Dollars in Millions) Assets Liabilities Assets Liabilities Pension Plans $ 41 $ — $ 125 $ — Other Employee Benefit Plans 182 — 272 — Accelerated Depreciation — 6,576 — 9,925 Other 657 722 225 293 Total $ 880 $ 7,298 $ 622 $ 10,218 Net Deferred Income Tax Liabilities $ 6,418 $ 9,596
Schedule of Change to Total Gross Unrecognized Tax Benefits	The change to the total gross unrecognized tax benefits and prior year audit resolutions of the Company during the fiscal year ended December 2017 is reconciled in the table below. Unrecognized Tax Benefits: Fiscal Year (Dollars in Millions) 2017 2016 2015 Balance at beginning of the year $ 25 $ 23 $ 21 Additions based on tax positions related to current year 1 1 1 Additions based on tax positions related to prior years 4 4 4 Reductions based on tax positions related to prior years — — — Settlements with taxing authorities (4 ) — 1 Lapse of statute of limitations (2 ) (3 ) (4 ) Balance at end of the year $ 24 $ 25 $ 23

Related Parties and Affiliates

Related Parties and Affiliates (Tables)	12 Months Ended
	Dec. 31, 2017
Related Party Transaction [Line Items]
Schedule of Minimum Rentals and Commitments under Operating Leases	At December 2017 , minimum rentals on land, buildings, track and equipment under operating leases are disclosed in the table below. Also, payments to Conrail for leases on shared rail infrastructure are included in these amounts. (See Note 12, Related Party Transactions ). (Dollars in Millions) Operating Sublease Net Lease Years Leases Income Commitments 2018 $ 68 $ (3 ) $ 65 2019 64 (3 ) 61 2020 50 (3 ) 47 2021 45 (3 ) 42 2022 41 (3 ) 38 Thereafter 128 (6 ) 122 Total $ 396 $ (21 ) $ 375
Corporate Joint Venture
Related Party Transaction [Line Items]
Schedule of Minimum Rentals and Commitments under Operating Leases	Future minimum lease payments due to Conrail under the shared asset area agreements are shown in the table below. (Dollars in Millions) Conrail Shared Years Asset Agreement 2018 $ 27 2019 27 2020 27 2021 27 2022 27 Thereafter 48 Total $ 183
Schedule of Related Party in the Consolidated Income Statement Components	The following table discloses amounts related to Conrail. Purchase price amortization and equity earnings are included in equity earnings of affiliates and all other amounts in the table are included in materials, supplies and other expenses on the Company’s consolidated income statements. Fiscal Years (Dollars in Millions) 2017 2016 2015 Rents, fees and services $ 120 $ 114 $ 123 Purchase price amortization and other 4 4 4 Equity earnings of Conrail (58 ) (37 ) (33 ) Total Conrail Expense $ 66 $ 81 $ 94
Schedule of Related Party Consolidated Balance Sheet Components	As required by the Related Party Disclosures Topic in the ASC, the Company has identified amounts below owed to Conrail, or its subsidiaries, representing liabilities under the operating, equipment and shared area agreements with Conrail. In 2014, the Company also executed two promissory notes with a subsidiary of Conrail which were included in long-term debt on the consolidated balance sheets. Interest expense from these promissory notes was $6 million for 2017 , 2016 and 2015 , respectively. December December (Dollars in Millions) 2017 2016 Balance Sheet Information: CSX payable to Conrail $ 123 $ 91 Promissory notes payable to Conrail subsidiary 2.89% CSX promissory note due October 2044 73 73 2.89% CSXT promissory note due October 2044 151 151
TTX Company
Related Party Transaction [Line Items]
Schedule of Related Party in the Consolidated Income Statement Components	As required by the Related Party Disclosures Topic in the ASC, the following table discloses amounts related to TTX. Car hire rents are included in equipment and other rents expense and equity earnings are included in equity earnings of affiliates in the Company’s consolidated income statements. Also included below is balance sheet information related to CSX's payable to TTX, which represents car rental liabilities. Fiscal Years (Dollars in Millions) 2017 2016 2015 Income statement information: Car hire rents $ 237 $ 233 $ 218 Equity earnings of TTX (157 ) (26 ) (20 ) Total TTX expense $ 80 $ 207 $ 198
Schedule of Related Party Consolidated Balance Sheet Components	December December Balance sheet information: 2017 2016 CSX payable to TTX $ 43 $ 47

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Investment Assets	The Company's investment assets are carried at fair value on the consolidated balance sheets as summarized in the following table. All of the inputs used to determine the fair value of the Company's investments are Level 2 inputs. The amortized cost basis of these investments was $91 million and $500 million as of December 31, 2017 and December 30, 2016 , respectively. NOTE 13. Fair Value Measurements, continued Fiscal Years 2017 2016 (Dollars in Millions) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Certificates of Deposit and Commercial Paper $ — $ — $ — $ — $ — $ 415 $ — $ 415 Corporate Bonds — 61 — 61 — 63 — 63 Government Securities — 34 — 34 — 22 — 22 Total investments at fair value $ — $ 95 $ — $ 95 $ — $ 500 $ — $ 500
Schedule of Investment Maturities	These investments have the following maturities and are represented on the consolidated balance sheet within short-term investments for investments with maturities of less than one year, and other long-term assets for investments with maturities of one year and greater: (Dollars in Millions) December 2017 December 2016 Less than 1 year $ 18 $ 417 1 - 2 years 3 12 2 - 5 years 8 4 Greater than 5 years 66 67 Total investments at fair value $ 95 $ 500
Schedule of Fair Value and Carrying Value of Long-term Debt	The fair value and carrying value of the Company's long-term debt is as follows: (Dollars in Millions) December 2017 December 2016 Long-term Debt (Including Current Maturities): Fair Value $ 13,220 $ 12,096 Carrying Value 11,809 11,293
Schedule of Pension Plan Assets at Fair Value by Level	The pension plan assets at fair value by level, within the fair value hierarchy, as of calendar plan years 2017 and 2016 are shown in the table below. For additional information related to pension assets, see Note 8, Employee Benefit Plans. Fiscal Years 2017 2016 (Dollars in Millions) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Common Stock $ 1,022 $ — $ — $ 1,022 $ 940 $ — $ — $ 940 Mutual funds 14 — — 14 12 — — 12 Cash equivalents 2 — — 2 1 — — 1 Corporate bonds — 537 — 537 — 497 — 497 Government securities — 169 — 169 — 141 — 141 Asset-backed securities — 9 — 9 — 14 — 14 Derivatives and other — 11 — 11 — 11 — 11 Total investments in the fair value hierarchy $ 1,038 $ 726 $ — $ 1,764 $ 953 $ 663 $ — $ 1,616 Investments measured at net asset value (a) n/a n/a n/a $ 1,069 n/a n/a n/a $ 923 Investments at fair value $ 1,038 $ 726 $ — $ 2,833 $ 953 $ 663 $ — $ 2,539 (a) Investments measured at net asset value represent certain investments that have been measured at net asset value per share (or its equivalent) and thus are not classified in the fair value hierarchy. In accordance with ASC 820, Fair Value Measurements, the fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the pension assets disclosed in Note 8, Employee Benefit Plans.

Other Comprehensive Income _ 39

Other Comprehensive Income / (Loss) (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Changes in the AOCI Balance by Component	Changes in the AOCI balance by component are shown in the table below. Amounts reclassified in pension and other post-employment benefits to net earnings relate to the amortization of actuarial losses and are included in labor and fringe on the consolidated income statements. See Note 8. Employee Benefit Plans for further information. Other primarily represents CSX's share of AOCI of equity method investees. Amounts reclassified in other to net earnings are included in materials, supplies and other on the consolidated income statements. Pension and Other Post-Employment Benefits Other Accumulated Other Comprehensive Income (Loss) (Dollars in millions) Balance December 26, 2014 - Net of Tax $ (611 ) $ (55 ) $ (666 ) Other Comprehensive Income(Loss) Loss Before Reclassifications (53 ) (8 ) (61 ) Amounts Reclassified to Net Earnings 71 (2 ) 69 Tax (Expense) Benefit (8 ) 1 (7 ) Total Other Comprehensive (Loss) Income 10 (9 ) 1 Balance December 25, 2015 - Net of Tax (601 ) (64 ) (665 ) Other Comprehensive Income (Loss) Income Before Reclassifications (16 ) 3 (13 ) Amounts Reclassified to Net Earnings 50 1 51 Tax Expense (13 ) — (13 ) Total Other Comprehensive Income 21 4 25 Balance December 30, 2016 - Net of Tax (580 ) (60 ) (640 ) Other Comprehensive Income Income Before Reclassifications 148 13 161 Amounts Reclassified to Net Earnings 56 2 58 Tax Expense (64 ) (1 ) (65 ) Total Other Comprehensive Income 140 14 154 Balance December 31, 2017 - Net of Tax $ (440 ) $ (46 ) $ (486 )

Quarterly Financial Data (Una40

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data	Pursuant to Article 3 of the SEC’s Regulation S-X, the following are selected quarterly financial data: Fiscal Year Ended December 2017 (a) Quarters (Dollars in Millions, Except Per Share Amounts) 1st 2nd 3rd 4th Full Year Revenue $ 2,869 $ 2,933 $ 2,743 $ 2,863 $ 11,408 Operating Income 712 958 876 1,121 3,667 Net Earnings (b) 362 510 459 4,140 5,471 Earnings Per Share, Basic (b) $ 0.39 $ 0.55 $ 0.51 $ 4.63 $ 6.01 Earnings Per Share, Assuming Dilution (b) 0.39 0.55 0.51 4.62 5.99 Fiscal Year Ended December 2016 (a) Revenue $ 2,618 $ 2,704 $ 2,710 $ 3,037 $ 11,069 Operating Income 704 840 841 1,004 3,389 Net Earnings 356 445 455 458 1,714 Earnings Per Share, Basic $ 0.37 $ 0.47 $ 0.48 $ 0.49 $ 1.81 Earnings Per Share, Assuming Dilution 0.37 0.47 0.48 0.49 1.81 (a) Prior to third quarter 2017, CSX followed a 52/53 week fiscal reporting calendar and 2016 included 53 weeks. All 2016 information presented in Results of Operations is on a 53-week basis, under Generally Accepted Accounting Principles ("GAAP"). See Note 1, Nature of Operations and Significant Accounting Policies for details regarding the number of days in each quarterly period presented. (b) These results for fourth quarter and full year 2017 include a $3.6 billion , or $3.91 per share, net tax reform benefit. See further discussion in Note 11, Income Taxes.

Summarized Consolidating Fina41

Summarized Consolidating Financial Data (Tables)	12 Months Ended
	Dec. 31, 2017
Summarized Consolidating Financial Data [Abstract]
Consolidating Income Statement	Consolidating Income Statements (Dollars in Millions) Fiscal Year Ended December 2017 CSX Corporation CSX Transportation Eliminations and Other CSX Consolidated Revenue $ — $ 11,334 $ 74 $ 11,408 Expense (158 ) 8,070 (171 ) 7,741 Operating Income 158 3,264 245 3,667 Equity in Earnings of Subsidiaries 5,810 — (5,810 ) — Interest Expense (582 ) (29 ) 65 (546 ) Other Income - Net 7 42 (28 ) 21 Earnings Before Income Taxes 5,393 3,277 (5,528 ) 3,142 Income Tax Benefit 78 2,247 4 2,329 Net Earnings $ 5,471 $ 5,524 $ (5,524 ) $ 5,471 Total Comprehensive Earnings $ 5,625 $ 5,538 $ (5,538 ) $ 5,625 Fiscal Year Ended December 2016 Revenue $ — $ 10,991 $ 78 $ 11,069 Expense (265 ) 8,100 (155 ) 7,680 Operating Income 265 2,891 233 3,389 Equity in Earnings of Subsidiaries 1,997 2 (1,999 ) — Interest Expense (583 ) (35 ) 39 (579 ) Other Income - Net (112 ) 44 (1 ) (69 ) Earnings Before Income Taxes 1,567 2,902 (1,728 ) 2,741 Income Tax Benefit (Expense) 147 (1,081 ) (93 ) (1,027 ) Net Earnings $ 1,714 $ 1,821 $ (1,821 ) $ 1,714 Total Comprehensive Earnings $ 1,739 $ 1,833 $ (1,833 ) $ 1,739 Fiscal Year Ended December 2015 Revenue $ — $ 11,733 $ 78 $ 11,811 Expense (589 ) 8,922 (106 ) 8,227 Operating Income 589 2,811 184 3,584 Equity in Earnings of Subsidiaries 1,949 — (1,949 ) — Interest Expense (539 ) (33 ) 28 (544 ) Other Income - Net (4 ) 111 (9 ) 98 Earnings Before Income Taxes 1,995 2,889 (1,746 ) 3,138 Income Tax Expense (27 ) (1,083 ) (60 ) (1,170 ) Net Earnings $ 1,968 $ 1,806 $ (1,806 ) $ 1,968 Total Comprehensive Earnings $ 1,969 $ 1,806 $ (1,806 ) $ 1,969
Consolidating Balance Sheets	Consolidating Balance Sheets (Dollars in Millions) As of December 31, 2017 CSX Corporation CSX Transportation Eliminations and Other CSX ASSETS Current Assets: Cash and Cash Equivalents $ 274 $ 121 $ 6 $ 401 Short-term Investments — — 18 18 Accounts Receivable - Net (1 ) 301 670 970 Receivable from Affiliates 1,226 3,517 (4,743 ) — Materials and Supplies — 372 — 372 Other Current Assets (1 ) 145 10 154 Total Current Assets 1,498 4,456 (4,039 ) 1,915 Properties 1 41,479 2,844 44,324 Accumulated Depreciation (1 ) (11,017 ) (1,542 ) (12,560 ) Properties - Net — 30,462 1,302 31,764 Investments in Conrail — — 907 907 Affiliates and Other Companies (39 ) 800 18 779 Investment in Consolidated Subsidiaries 29,405 — (29,405 ) — Other Long-term Assets 39 596 (261 ) 374 Total Assets $ 30,903 $ 36,314 $ (31,478 ) $ 35,739 LIABILITIES AND SHAREHOLDERS' EQUITY Current Liabilities: Accounts Payable $ 105 $ 708 $ 34 $ 847 Labor and Fringe Benefits Payable 52 494 56 602 Payable to Affiliates 4,792 552 (5,344 ) — Casualty, Environmental and Other Reserves — 95 13 108 Current Maturities of Long-term Debt — 19 — 19 Income and Other Taxes Payable (326 ) 455 28 157 Other Current Liabilities 5 153 3 161 Total Current Liabilities 4,628 2,476 (5,210 ) 1,894 Casualty, Environmental and Other Reserves — 222 44 266 Long-term Debt 11,056 733 1 11,790 Deferred Income Taxes - Net (130 ) 6,342 206 6,418 Other Long-term Liabilities 644 320 (314 ) 650 Total Liabilities 16,198 10,093 (5,273 ) 21,018 Shareholders' Equity: Common Stock, $1 Par Value 890 181 (181 ) 890 Other Capital 217 5,096 (5,096 ) 217 Retained Earnings 14,084 20,933 (20,933 ) 14,084 Accumulated Other Comprehensive Loss (486 ) (5 ) 5 (486 ) Noncontrolling Minority Interest — 16 — 16 Total Shareholders' Equity 14,705 26,221 (26,205 ) 14,721 Total Liabilities and Shareholders' Equity $ 30,903 $ 36,314 $ (31,478 ) $ 35,739 NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Balance Sheets (Dollars in Millions) As of December 30, 2016 CSX Corporation CSX Transportation Eliminations and Other CSX ASSETS Current Assets Cash and Cash Equivalents $ 305 $ 281 $ 17 $ 603 Short-term Investments 415 — 2 417 Accounts Receivable - Net 2 215 721 938 Receivable from Affiliates 1,157 2,351 (3,508 ) — Materials and Supplies — 407 — 407 Other Current Assets — 106 16 122 Total Current Assets 1,879 3,360 (2,752 ) 2,487 Properties 1 40,518 2,708 43,227 Accumulated Depreciation (1 ) (10,634 ) (1,442 ) (12,077 ) Properties - Net — 29,884 1,266 31,150 Investments in Conrail — — 840 840 Affiliates and Other Companies (39 ) 643 15 619 Investment in Consolidated Subsidiaries 24,179 — (24,179 ) — Other Long-term Assets 2 607 (291 ) 318 Total Assets $ 26,021 $ 34,494 $ (25,101 ) $ 35,414 LIABILITIES AND SHAREHOLDERS' EQUITY Current Liabilities Accounts Payable $ 95 $ 678 $ 33 $ 806 Labor and Fringe Benefits Payable 40 440 65 545 Payable to Affiliates 3,457 500 (3,957 ) — Casualty, Environmental and Other Reserves — 102 13 115 Current Maturities of Long-term Debt 313 19 (1 ) 331 Income and Other Taxes Payable (346 ) 459 16 129 Other Current Liabilities — 112 2 114 Total Current Liabilities 3,559 2,310 (3,829 ) 2,040 Casualty, Environmental and Other Reserves — 208 51 259 Long-term Debt 10,203 759 — 10,962 Deferred Income Taxes - Net (203 ) 9,541 258 9,596 Other Long-term Liabilities 783 410 (330 ) 863 Total Liabilities 14,342 13,228 (3,850 ) 23,720 Shareholders' Equity Common Stock, $1 Par Value 928 181 (181 ) 928 Other Capital 138 5,095 (5,095 ) 138 Retained Earnings 11,253 15,994 (15,994 ) 11,253 Accumulated Other Comprehensive Loss (640 ) (19 ) 19 (640 ) Noncontrolling Minority Interest — 15 — 15 Total Shareholders' Equity 11,679 21,266 (21,251 ) 11,694 Total Liabilities and Shareholders' Equity $ 26,021 $ 34,494 $ (25,101 ) $ 35,414
Consolidating Cash Flow Statements	Consolidating Cash Flow Statements (Dollars in Millions) Fiscal Year Ended December 2017 CSX Corporation CSX Transportation Eliminations and Other CSX Operating Activities Net Cash Provided by (Used in) Operating Activities $ 1,719 $ 2,112 $ (359 ) $ 3,472 Investing Activities Property Additions — (1,848 ) (192 ) (2,040 ) Purchases of Short-term Investments (774 ) — (8 ) (782 ) Proceeds from Sales of Short-term Investments 1,190 — 3 1,193 Proceeds from Property Dispositions — 97 — 97 Other Investing Activities (2 ) 94 (55 ) 37 Net Cash Provided by (Used in) Investing Activities 414 (1,657 ) (252 ) (1,495 ) Financing Activities Long-term Debt Issued 850 — — 850 Long-term Debt Repaid (313 ) (20 ) — (333 ) Dividends Paid (708 ) (600 ) 600 (708 ) Shares Repurchased (1,970 ) — — (1,970 ) Other Financing Activities (23 ) 5 — (18 ) Net Cash Provided by (Used in) Financing Activities (2,164 ) (615 ) 600 (2,179 ) Net Decrease in Cash and Cash Equivalents (31 ) (160 ) (11 ) (202 ) Cash and Cash Equivalents at Beginning of Period 305 281 17 603 Cash and Cash Equivalents at End of Period $ 274 $ 121 $ 6 $ 401 NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Cash Flow Statements (Dollars in Millions) Fiscal Year Ended December 2016 CSX Corporation CSX Transportation Eliminations and Other CSX Operating Activities Net Cash Provided by (Used in) Operating Activities $ 453 $ 2,950 $ (362 ) $ 3,041 Investing Activities Property Additions — (2,208 ) (190 ) (2,398 ) Purchases of Short-term Investments (929 ) — — (929 ) Proceeds from Sales of Short-term Investments 1,325 — — 1,325 Proceeds from Property Dispositions — 195 — 195 Other Investing Activities (41 ) 91 (41 ) 9 Net Cash Provided by (Used in) Investing Activities 355 (1,922 ) (231 ) (1,798 ) Financing Activities Long-term Debt Issued 2,200 — — 2,200 Long-term Debt Repaid (1,400 ) (19 ) — (1,419 ) Dividends Paid (680 ) (600 ) 600 (680 ) Shares Repurchased (1,056 ) — — (1,056 ) Other Financing Activities (11 ) (303 ) 1 (313 ) Net Cash Provided by (Used in) Financing Activities (947 ) (922 ) 601 (1,268 ) Net (Decrease) Increase in Cash and Cash Equivalents (139 ) 106 8 (25 ) Cash and Cash Equivalents at Beginning of Period 444 175 9 628 Cash and Cash Equivalents at End of Period $ 305 $ 281 $ 17 $ 603 NOTE 16. Summarized Consolidating Financial Data, continued Consolidating Cash Flow Statements (Dollars in Millions) Fiscal Year Ended December 2015 CSX Corporation CSX Transportation Eliminations and Other CSX Operating Activities Net Cash Provided by (Used in) Operating Activities $ 983 $ 2,974 $ (587 ) $ 3,370 Investing Activities Property Additions — (2,400 ) (162 ) (2,562 ) Purchases of Short-term Investments (1,734 ) — (5 ) (1,739 ) Proceeds from Sales of Short-term Investments 1,175 — 50 1,225 Proceeds from Property Dispositions — 147 — 147 Other Investing Activities (10 ) 132 (85 ) 37 Net Cash Provided by (Used in) Investing Activities (569 ) (2,121 ) (202 ) (2,892 ) Financing Activities Long-term Debt Issued 1,200 — — 1,200 Long-term Debt Repaid (200 ) (29 ) — (229 ) Dividends Paid (686 ) (750 ) 750 (686 ) Shares Repurchased (804 ) — — (804 ) Other Financing Activities 10 1 (11 ) — Net Cash Provided by (Used in) Financing Activities (480 ) (778 ) 739 (519 ) Net (Decrease) Increase in Cash and Cash Equivalents (66 ) 75 (50 ) (41 ) Cash and Cash Equivalents at Beginning of Period 510 100 59 669 Cash and Cash Equivalents at End of Period $ 444 $ 175 $ 9 $ 628

Nature of Operations and Sign42

Nature of Operations and Significant Accounting Policies - Narrative (Details) mi in Thousands, carload in Thousands, shares in Millions, $ in Millions	Jun. 05, 2017	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)employeerailroadport_terminalstateterminalmi	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 30, 2016USD ($)	Sep. 23, 2016USD ($)	Jun. 24, 2016USD ($)	Mar. 25, 2016USD ($)	Dec. 31, 2017USD ($)employeerailroadcarloadport_terminalstateterminalmishares	Dec. 30, 2016USD ($)shares	Dec. 25, 2015USD ($)shares
Revenue from External Customer [Line Items]
Number of employees | employee			24,000								24,000
Number of union employees | employee											20,000
Number of rail route miles | mi			21								21
Rail network states number | state			23								23
Number of short-line and regional railroads served | railroad			230								230
Revenue			$ 2,863	$ 2,743	$ 2,933	$ 2,869	$ 3,037	$ 2,710	$ 2,704	$ 2,618	$ 11,408	$ 11,069	$ 11,811
Cost method, maximum percentage											20.00%
Cash equivalents maximum maturity period (in months)											3 months
Short-term investments, minimum maturity period											3 months
Short-term investments, maximum maturity period											1 year
Allowance for doubtful accounts			26				33				$ 26	33
Goodwill			63				$ 63				63	63
Pension and other post retirement benefit settlement charges											85
Shares acquired, repurchase amount											$ 1,970	$ 1,056	$ 804
Stock repurchased (in shares) | shares											39	38	26
Shareholder vote percent	93.00%
Separation costs												$ 0	$ 51
Management streamlining
Revenue from External Customer [Line Items]
Workforce reduction (number of employees) | employee											950
Chief Executive Officer
Revenue from External Customer [Line Items]
Reimbursement payment		$ 55
Lump sum cash payment			$ 29								$ 29
Minimum
Revenue from External Customer [Line Items]
Number of ocean, river and lake ports serviced (more than) | port_terminal			70								70
Merchandise business
Revenue from External Customer [Line Items]
Number of carloads | carload											2,700
Percentage of total revenue											62.00%
Percentage of total volume											42.00%
Coal business
Revenue from External Customer [Line Items]
Number of carloads | carload											855
Percentage of total revenue											18.00%
Percentage of total volume											13.00%
Intermodal business
Revenue from External Customer [Line Items]
Percentage of total revenue											16.00%
Percentage of total volume											44.00%
Number of terminals (more than) | terminal			40								40
Other business
Revenue from External Customer [Line Items]
Percentage of total revenue											4.00%

Nature of Operations and Sign43

Nature of Operations and Significant Accounting Policies - Schedule of Retrospective Impact of Future Adoption (Details) - Pro Forma - Accounting Standards Update 2017-07 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in Operating Income	$ 53	$ 24	$ 44
Decrease in Other Income	$ (53)	$ (24)	$ (44)

Nature of Operations and Sign44

Nature of Operations and Significant Accounting Policies - Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)					$ 325	$ 0	$ 0
Cash Payments for Restructuring Charge					(187)	$ 0	$ 0
Management streamlining
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	$ 29	$ 1	$ 122	$ 173	325
Cash Payments for Restructuring Charge					(187)
Non-cash Items					(124)
Liability	14				14
Management streamlining | Subtotal Management Workforce Reduction
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	17	0	22	155	194
Cash Payments for Restructuring Charge					(92)
Non-cash Items					(88)
Liability	14				14
Management streamlining | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	7	0	10	81	98
Cash Payments for Restructuring Charge					(86)
Non-cash Items					0
Liability	12				12
Management streamlining | Pension and Other Post-Retirement Benefit Charges
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	3	0	7	63	73
Cash Payments for Restructuring Charge					0
Non-cash Items					(73)
Liability	0				0
Management streamlining | Share-Based Compensation Remeasurement
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	7	0	3	5	15
Cash Payments for Restructuring Charge					0
Non-cash Items					(15)
Liability	0				0
Management streamlining | Relocation
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	0	0	2	6	8
Cash Payments for Restructuring Charge					(6)
Non-cash Items					0
Liability	2				2
Management streamlining | Reimbursement Arrangements
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	0	0	84	0	84
Cash Payments for Restructuring Charge					(84)
Non-cash Items					0
Liability	0				0
Management streamlining | Non-Cash Executive Equity Awards Proration
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	0	0	16	8	24
Cash Payments for Restructuring Charge					0
Non-cash Items					(24)
Liability	0				0
Management streamlining | Non-Cash Pension Settlement Charge
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	12	0	0	0	12
Cash Payments for Restructuring Charge					0
Non-cash Items					(12)
Liability	0				0
Management streamlining | Other Charges Including Fees Related to Shareholder Matters
Restructuring Cost and Reserve [Line Items]
Restructuring Charge (Note 1)	0	$ 1	$ 0	$ 10	11
Cash Payments for Restructuring Charge					(11)
Non-cash Items					0
Liability	$ 0				$ 0

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted 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. 30, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Numerator:
Net Earnings	$ 4,140	$ 459	$ 510	$ 362	$ 458	$ 455	$ 445	$ 356	$ 5,471	$ 1,714	$ 1,968
Dividend Equivalents on Restricted Stock									(1)	(1)	(1)
Net Earnings, Attributable to Common Shareholders									$ 5,470	$ 1,713	$ 1,967
Denominator:
Average Common Shares Outstanding (in shares)									911	947	983
Other Potentially Dilutive Common Shares (in shares)									3	1	1
Average Common Shares Outstanding, Assuming Dilution (in shares)									914	948	984
Basic (in dollars per share)	$ 4.63	$ 0.51	$ 0.55	$ 0.39	$ 0.49	$ 0.48	$ 0.47	$ 0.37	$ 6.01	$ 1.81	$ 2
Assuming Dilution (in dollars per share)	$ 4.62	$ 0.51	$ 0.55	$ 0.39	$ 0.49	$ 0.48	$ 0.47	$ 0.37	$ 5.99	$ 1.81	$ 2

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - USD ($) shares in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2017	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015	Oct. 25, 2017	Apr. 30, 2017	Apr. 30, 2015
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)		7.6	2.8	2.5
Share Repurchase Program April 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share repurchase program							$ 2,000,000,000
Share Repurchase Program April 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share repurchase program						$ 1,000,000,000
Share repurchase program, additional authorized amount	$ 500,000,000
Share Repurchase Program October 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share repurchase program					$ 1,500,000,000

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Earnings Per Share [Abstract]
Stock repurchased (in shares)	39	38	26
Cost of Shares	$ 1,970	$ 1,056	$ 804

Shareholders' Equity (Details)

Shareholders' Equity (Details) - $ / shares	Dec. 31, 2017	Dec. 30, 2016
Class of Stock [Line Items]
Common stock par value (in dollars per share)	$ 1	$ 1
Common Stock
Class of Stock [Line Items]
Common Shares Authorized (in shares)	1,800,000,000
Common Shares Issued (in shares)	890,000,000
Common Shares Outstanding (in shares)	890,000,000
Preferred Stock
Class of Stock [Line Items]
Preferred Shares Authorized (in shares)	25,000,000
Preferred Shares Issued (in shares)	0
Preferred Shares Outstanding (in shares)	0

Stock Plans and Share-Based C49

Stock Plans and Share-Based Compensation - Schedule of Share-Based Compensation and Related Income Tax Benefit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Share-based Compensation Expense	$ 89	$ 37	$ 12
Income Tax Benefit	34	14	4
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Share-based Compensation Expense	49	17	(1)
Restricted Stock Units and Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Share-based Compensation Expense	15	11	11
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Share-based Compensation Expense	22	7	0
Stock Awards for Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Share-based Compensation Expense	$ 3	$ 2	$ 2

Stock Plans and Share-Based C50

Stock Plans and Share-Based Compensation - Narrative (Details)	Dec. 16, 2017shares	Mar. 06, 2017$ / sharesshares	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)employeeplan$ / sharesshares	Dec. 30, 2016$ / sharesshares	Dec. 25, 2015$ / shares
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock options granted (in dollars per share) | $ / shares		$ 12.88
Options forfeited (in shares) | shares	9,000,000
Chairman
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Lump sum payment | $			$ 250,000
Vesting Upon Service Anniversary | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Nonvested stock options (in shares) | shares		4,500,000
Vesting Upon Achievement of Performance Targets | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				4 years
Nonvested stock options (in shares) | shares				4,500,000
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost | $				$ 24,000,000
Expected weighted average period of recognition for unrecognized compensation cost (in years)				2 years
Restricted Stock Units and Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				3 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				5 years
Unrecognized compensation cost | $				$ 7,000,000
Expected weighted average period of recognition for unrecognized compensation cost (in years)				1 year
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost | $				$ 10,000,000
Expected weighted average period of recognition for unrecognized compensation cost (in years)				1 year
Expected life (in years)				6 years 3 months	6 years 6 months	6 years 6 months
Stock options granted (in shares) | shares				10,462,000
Fair value of stock options granted (in dollars per share) | $ / shares				$ 12.84	$ 4.68	$ 5.31
Nonvested stock options (in shares) | shares				4,163,000	4,582,000
Stock Options | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term		10 years
Long-term Incentive Plans | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range (as a percent)				0.00%
Long-term Incentive Plans | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range (as a percent)				200.00%
Long-term Incentive Plans | Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance unit equivalent of CSX stock (in shares) | shares				1
Number of plans | plan				3
Payout percentage cumulative period				3 years
Percentage payout on operating ratio				50.00%
Percentage payout on average return on assets				50.00%
Percentage of payout subject to reduction (up to)				30.00%
Long-term Incentive Plans | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance unit equivalent of CSX stock (in shares) | shares				1
Long-term Incentive Plans | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option requisite service period				3 years
Award term				10 years
Long Term Incentive Plans 2015-2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				3 years
Long Term Incentive Plan 2016-2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				3 years
Long Term Incentive Plan 2017-2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				3 years
Equity Award Modifications
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees impacted (employees) | employee				75
Share-based compensation expense revaluation of awards | $				$ 39,000,000
Non-management Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual retainer to be paid to non-management directors, cash option | $				100,000
Annual retainer to be paid to non-management directors, common stock option | $				$ 150,000
Long Term Incentive Plan Year One | Performance Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range (as a percent)				0.00%
Long Term Incentive Plan Year One | Performance Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range (as a percent)				200.00%
Long Term Incentive Plan Year Two | Performance Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range (as a percent)				0.00%
Long Term Incentive Plan Year Two | Performance Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range (as a percent)				200.00%
Long Term Incentive Plan Year Three | Performance Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range (as a percent)				0.00%
Long Term Incentive Plan Year Three | Performance Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range (as a percent)				200.00%

Stock Plans and Share-Based C51

Stock Plans and Share-Based Compensation - Summary of Performance Unit Grant and Vesting Information (Details) - Performance Units - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value (in dollars per share)	$ 49.50	$ 24.17	$ 35.45
Fair value of units vested in fiscal year ending (in millions)	$ 26	$ 31	$ 34

Stock Plans and Share-Based C52

Stock Plans and Share-Based Compensation - Performance Unit Activity Related to Outstanding Long-term Incentive Plans and Corresponding Fair Value (Details) - Performance Units shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Weighted-Average Fair Value at Grant Date
Unvested, Weighted-Average Fair Value at Grant Date, beginning of period (in dollars per share)	$ 24.17
Unvested, Weighted-Average Fair Value at Grant Date, end of period (in dollars per share)	$ 49.50
Long-term Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, Units Outstanding, beginning balance (in shares) | shares	1,581
Granted (in shares) | shares	644
Forfeited (in shares) | shares	(530)
Vested (in shares) | shares	(719)
Unvested, Units Outstanding, ending balance (in shares) | shares	976
Weighted-Average Fair Value at Grant Date
Unvested, Weighted-Average Fair Value at Grant Date, beginning of period (in dollars per share)	$ 30
Granted (in dollars per share)	49.50
Forfeited (in dollars per share)	38.47
Vested (in dollars per share)	35.94
Unvested, Weighted-Average Fair Value at Grant Date, end of period (in dollars per share)	$ 33.90

Stock Plans and Share-Based C53

Stock Plans and Share-Based Compensation - Summary of Restricted Stock Grant and Vesting Information (Details) - Restricted Stock - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value (in dollars per share)	$ 48.35	$ 24.21	$ 35.94
Fair value of units vested in fiscal year ending (in millions)	$ 8	$ 14	$ 9

Stock Plans and Share-Based C54

Stock Plans and Share-Based Compensation - Schedule of Outstanding Restricted Stock Units and Award (Details) - Restricted Stock shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, Units Outstanding, beginning balance (in shares) | shares	1,076
Granted (in shares) | shares	328
Forfeited (in shares) | shares	(297)
Vested (in shares) | shares	(300)
Unvested, Units Outstanding, ending balance (in shares) | shares	807
Weighted-Average Fair Value at Grant Date
Unvested, Weighted-Average Fair Value at Grant Date, beginning of period (in dollars per share) | $ / shares	$ 28.19
Granted (in dollars per share) | $ / shares	48.35
Forfeited (in dollars per share) | $ / shares	36.48
Vested (in dollars per share) | $ / shares	28.09
Unvested, Weighted-Average Fair Value at Grant Date, end of period (in dollars per share) | $ / shares	$ 33.37

Stock Plans and Share-Based C55

Stock Plans and Share-Based Compensation - Summary of Assumptions and Inputs Used to Estimate Fair Value of Stock Options (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock options granted (in dollars per share)	$ 12.84	$ 4.68	$ 5.31
Annual dividend yield (as a percent)	1.50%	3.00%	3.00%
Risk-free interest rate (as a percent)	2.20%	1.00%	2.00%
Annualized volatility (as a percent)	27.10%	27.00%	28.00%
Expected life (in years)	6 years 3 months	6 years 6 months	6 years 6 months
Weighted-average grant-date market price of CSX stock (strike price)	$ 49.63	$ 24.13	$ 24.99

Stock Plans and Share-Based C56

Stock Plans and Share-Based Compensation - Summary of Stock Option Activity (Details) - Stock Options shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Outstanding beginning of period (in shares) | shares	4,582
Granted (in shares) | shares	10,462
Forfeited (in shares) | shares	(10,860)
Exercised (in shares) | shares	22
Outstanding end of period (in shares) | shares	4,163
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 24.57
Granted (in dollars per share) | $ / shares	49.63
Forfeited (in dollars per share) | $ / shares	46.81
Exercised (in dollars per share) | $ / shares	25.18
Outstanding at end of period (in dollars per share) | $ / shares	$ 29.52
Exercisable (in shares) | shares	0
Exercisable (in dollars per share) | $ / shares	$ 0

Casualty, Environmental and O57

Casualty, Environmental and Other Reserves - Schedule of Claims Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	$ 374	$ 400	$ 418
Charged to Expense	114	128	142
Change in Estimate		(28)
Payments	(114)	(126)	(160)
Balance end of period	374	374	400
Casualty Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	229	269	265
Charged to Expense	43	52	60
Change in Estimate		(28)
Payments	(44)	(64)	(56)
Balance end of period	228	229	269
Environmental Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	95	82	94
Charged to Expense	26	46	45
Change in Estimate		0
Payments	(31)	(33)	(57)
Balance end of period	90	95	82
Other Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	50	49	59
Charged to Expense	45	30	37
Change in Estimate		0
Payments	(39)	(29)	(47)
Balance end of period	$ 56	$ 50	$ 49

Casualty, Environmental and O58

Casualty, Environmental and Other Reserves - Casualty, Environmental and Other Reserves (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015	Dec. 26, 2014
Contingencies [Line Items]
Current	$ 108	$ 115
Long-term	266	259
Total	374	374	$ 400	$ 418
Casualty Reserves
Contingencies [Line Items]
Current	49	53
Long-term	179	176
Total	228	229	269	265
Personal Injury
Contingencies [Line Items]
Current	43	46
Long-term	125	124
Total	168	170
Occupational
Contingencies [Line Items]
Current	6	7
Long-term	54	52
Total	60	59
Environmental
Contingencies [Line Items]
Current	31	42
Long-term	59	53
Total	90	95	82	94
Other Reserves
Contingencies [Line Items]
Current	28	20
Long-term	28	30
Total	$ 56	$ 50	$ 49	$ 59

Casualty, Environmental and O59

Casualty, Environmental and Other Reserves - Narrative (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)claimsite$ / shares	Sep. 30, 2017$ / shares	Jun. 30, 2017$ / shares	Mar. 31, 2017$ / shares	Dec. 30, 2016USD ($)$ / shares	Sep. 23, 2016$ / shares	Jun. 24, 2016$ / shares	Mar. 25, 2016$ / shares	Dec. 31, 2017USD ($)claimsite$ / shares	Dec. 30, 2016USD ($)$ / shares	Dec. 25, 2015USD ($)$ / shares	Dec. 26, 2014USD ($)
Loss Contingencies [Line Items]
Reserves	$ 374,000,000				$ 374,000,000				$ 374,000,000	$ 374,000,000	$ 400,000,000	$ 418,000,000
Reduction in reserves										$ (28,000,000)
Earnings per share impact (in dollars per share) | $ / shares	$ 4.63	$ 0.51	$ 0.55	$ 0.39	$ 0.49	$ 0.48	$ 0.47	$ 0.37	$ 6.01	$ 1.81	$ 2
Casualty Reserves
Loss Contingencies [Line Items]
Reserves	$ 228,000,000				$ 229,000,000				$ 228,000,000	$ 229,000,000	$ 269,000,000	265,000,000
Self-insured retention amount per injury									$ 50,000,000
Individual claims expected to exceed self-insured retention amount | claim	0								0
Change in estimate recorded to adjust reserves											0
Reduction in reserves										(28,000,000)
Earnings from continuing operations										$ 18,000,000
Earnings per share impact (in dollars per share) | $ / shares										$ 0.02
Environmental
Loss Contingencies [Line Items]
Reserves	$ 90,000,000				95,000,000				$ 90,000,000	$ 95,000,000	82,000,000	94,000,000
Reduction in reserves										0
Environmental impaired site | site	214								214
Other Reserves
Loss Contingencies [Line Items]
Reserves	$ 56,000,000				$ 50,000,000				$ 56,000,000	50,000,000	$ 49,000,000	$ 59,000,000
Reduction in reserves										$ 0

Properties - Schedule of Net Pr

Properties - Schedule of Net Properties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 44,324	$ 43,227
Accumulated Depreciation	(12,560)	(12,077)
Properties - Net	31,764	31,150
Total Road
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	30,091	28,824
Accumulated Depreciation	(7,790)	(7,324)
Properties - Net	22,301	21,500
Rail and Other Track Material
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	7,694	7,326
Accumulated Depreciation	(1,606)	(1,493)
Properties - Net	$ 6,088	$ 5,833
Annual Depreciation Rate	2.50%	2.50%
Estimated useful life	40 years	40 years
Ties
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 5,665	$ 5,368
Accumulated Depreciation	(1,446)	(1,292)
Properties - Net	$ 4,219	$ 4,076
Annual Depreciation Rate	3.70%	3.70%
Estimated useful life	27 years	27 years
Grading
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,662	$ 2,600
Accumulated Depreciation	(542)	(514)
Properties - Net	$ 2,120	$ 2,086
Annual Depreciation Rate	1.40%	1.40%
Estimated useful life	90 years	90 years
Ballast
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,994	$ 2,897
Accumulated Depreciation	(921)	(860)
Properties - Net	$ 2,073	$ 2,037
Annual Depreciation Rate	2.70%	2.70%
Estimated useful life	37 years	37 years
Bridges, Trestles, and Culverts
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,405	$ 2,306
Accumulated Depreciation	(356)	(317)
Properties - Net	$ 2,049	$ 1,989
Annual Depreciation Rate	1.60%	1.60%
Estimated useful life	70 years	70 years
Signals and Interlockers
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,759	$ 2,523
Accumulated Depreciation	(588)	(496)
Properties - Net	$ 2,171	$ 2,027
Annual Depreciation Rate	4.00%	4.00%
Estimated useful life	25 years	25 years
Buildings
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 1,278	$ 1,238
Accumulated Depreciation	(464)	(447)
Properties - Net	$ 814	$ 791
Annual Depreciation Rate	2.50%	2.50%
Estimated useful life	40 years	40 years
Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 4,634	$ 4,566
Accumulated Depreciation	(1,867)	(1,905)
Properties - Net	$ 2,767	$ 2,661
Annual Depreciation Rate	4.20%	4.20%
Estimated useful life	24 years	24 years
Total Equipment
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 11,606	$ 11,604
Accumulated Depreciation	(4,770)	(4,740)
Properties - Net	6,836	6,864
Locomotive
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	6,083	6,110
Accumulated Depreciation	(2,490)	(2,504)
Properties - Net	$ 3,593	$ 3,606
Annual Depreciation Rate	3.50%	3.50%
Estimated useful life	29 years	29 years
Freight Cars
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 3,262	$ 3,386
Accumulated Depreciation	(998)	(1,046)
Properties - Net	$ 2,264	$ 2,340
Annual Depreciation Rate	2.90%	2.90%
Estimated useful life	35 years	35 years
Work Equipment and Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 2,261	$ 2,108
Accumulated Depreciation	(1,282)	(1,190)
Properties - Net	$ 979	$ 918
Annual Depreciation Rate	7.40%	7.40%
Estimated useful life	14 years	14 years
Land
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 1,849	$ 1,833
Properties - Net	1,849	1,833
Construction In Progress
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	778	913
Properties - Net	$ 778	913
Other
Property, Plant and Equipment, Net, by Type [Abstract]
Cost		53
Accumulated Depreciation		(13)
Properties - Net		$ 40
Estimated useful life		32 years

Properties - Narrative (Details

Properties - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Property, Plant and Equipment [Line Items]
Percentage of labor costs relating to the deconstruction of old track	20.00%
Percentage of labor costs relating to the installation of new track	80.00%
Percentage of assets depreciated under the group-life method	86.00%
Total fixed assets	$ 44,324,000,000	$ 43,227,000,000
Depreciation	1,315,000,000	1,301,000,000	$ 1,208,000,000
Abnormal gains and losses	14,000,000	110,000,000
Impairment expense	25,000,000	0	0
Ties
Property, Plant and Equipment [Line Items]
Total fixed assets	$ 5,665,000,000	$ 5,368,000,000
Estimated useful life	27 years	27 years
Total Equipment
Property, Plant and Equipment [Line Items]
Total fixed assets	$ 11,606,000,000	$ 11,604,000,000
Life studies, frequency period	3 years
Total Road
Property, Plant and Equipment [Line Items]
Total fixed assets	$ 30,091,000,000	28,824,000,000
Life studies, frequency period	6 years
Abnormal gain (loss) on operating property
Property, Plant and Equipment [Line Items]
Abnormal gains and losses	$ 0	$ 0	0
Gain (loss) on non-operating property
Property, Plant and Equipment [Line Items]
Abnormal gains and losses			$ 59,000,000

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details)	1 Months Ended		12 Months Ended
	Mar. 31, 2016mi	May 31, 2007entity	Dec. 31, 2017USD ($)mi	Dec. 30, 2016USD ($)
Operating Leased Assets [Line Items]
Maximum lease term (up to)			30 years
Locomotive fleet covered by maintenance program (as a percent)			50.00%
Estimated obligation under maintenance program			$ 4,217,000,000
Non-catastrophic property deductible			25,000,000
Casualty and catastrophic property deductible			$ 50,000,000
Fuel Surcharge Antitrust Litigation
Operating Leased Assets [Line Items]
Number of other U.S.-based entities mentioned in class action lawsuit | entity		3
Environmental Litigation
Operating Leased Assets [Line Items]
Number of miles pertaining to Passaic River tidal reach required to be studied by EPA | mi			17
Number of miles under study | mi	8
Years to clean up site			10 years
Minimum | Pending Litigation
Operating Leased Assets [Line Items]
Range of possible loss from legal proceedings			$ 2,000,000
Maximum | Pending Litigation
Operating Leased Assets [Line Items]
Range of possible loss from legal proceedings			117,000,000
Locomotive Maintenance Payments
Operating Leased Assets [Line Items]
Estimated obligation under maintenance program			$ 3,715,000,000	$ 4,900,000,000

Commitments and Contingencies63

Commitments and Contingencies - Schedule of Rent Expense Associated with Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Rent Expense on Operating Leases
Operating Leased Assets [Line Items]
Rent Expense on Operating Leases	$ 78	$ 77	$ 86

Commitments and Contingencies64

Commitments and Contingencies - Schedule of Minimum Rentals and Commitments under Operating Leases (Details) $ in Millions	Dec. 31, 2017USD ($)
Operating Leases [Abstract]
2,018	$ 68
2,019	64
2,020	50
2,021	45
2,022	41
Thereafter	128
Total	396
Sublease Income [Abstract]
2,018	(3)
2,019	(3)
2,020	(3)
2,021	(3)
2,022	(3)
Thereafter	(6)
Total	(21)
Net Lease Commitments [Abstract]
2,018	65
2,019	61
2,020	47
2,021	42
2,022	38
Thereafter	122
Total	$ 375

Commitments and Contingencies65

Commitments and Contingencies - Schedule of Number of Locomotives and Payments under Long-term Maintenance Program (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)locomotive	Dec. 30, 2016USD ($)locomotive	Dec. 25, 2015USD ($)locomotive
Commitments and Contingencies Disclosure [Abstract]
Amounts Paid | $	$ 197	$ 230	$ 233
Number of Locomotives | locomotive	2,062	2,243	2,310

Commitments and Contingencies66

Commitments and Contingencies - Schedule of Annual Payments under Long-term Maintenance Program (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Unrecorded Unconditional Purchase Obligation [Abstract]
2,018	$ 290
2,019	229
2,020	253
2,021	258
2,022	258
Thereafter	2,929
Total	4,217
Locomotive Maintenance Payments
Unrecorded Unconditional Purchase Obligation [Abstract]
2,018	171
2,019	162
2,020	218
2,021	223
2,022	225
Thereafter	2,716
Total	3,715	$ 4,900
Other Commitments
Unrecorded Unconditional Purchase Obligation [Abstract]
2,018	119
2,019	67
2,020	35
2,021	35
2,022	33
Thereafter	213
Total	$ 502

Employee Benefit Plans - Summar

Employee Benefit Plans - Summary of Participants (Details)	Jan. 01, 2017employee
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Active Employees	3,744
Retirees and Beneficiaries	12,723
Other	3,591
Total	20,058
Post-retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Active Employees	458
Retirees and Beneficiaries	9,940
Other	36
Total	10,434

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	$ 0	$ 250,000,000	$ 0
Expected future contributions	0
Pension plan assets at fair value	2,833,000,000	2,539,000,000
Special termination benefits	56,000,000
Amount of premium expenses incurred under the plan	40,000,000	35,000,000	32,000,000
Expense associated with savings plans	39,000,000	35,000,000	36,000,000
Change in Assumptions for Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Decrease in net periodic pension expense	25,000,000
Post-retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	$ 0	0
Curtailment loss	$ 13,000,000
Discount rate (as a percent)	3.34%	3.71%
Special termination benefits	$ 13,000,000	$ 0	0
Pre-tax losses to be amortized	7,000,000
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2,833,000,000	$ 2,539,000,000	2,309,000,000
Curtailment loss	$ 4,000,000
Discount rate (as a percent)	3.56%	4.08%
Decrease to pension liabilities	$ 85,000,000
Special termination benefits	60,000,000	$ 0	$ 7,000,000
Pre-tax losses to be amortized	$ 705,000,000
Equity
Defined Benefit Plan Disclosure [Line Items]
Investment committee equity target allocation percentage of pension assets	70.00%
Targeted allocation of total plan assets in domestic equity (as a percent)	42.00%
Targeted allocation of total plan assets in international equity (as a percent)	28.00%
Percentage within which the planned allocation is managed (as a percent)	3.00%
Pension plan assets at fair value	$ 2,060,000,000	1,806,000,000
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Investment committee equity target allocation percentage of pension assets	30.00%
Pension plan assets at fair value	$ 729,000,000	665,000,000
Nonqualified Plan | Post-retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	29,000,000	32,000,000
Nonqualified Plan | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	45,000,000	17,000,000
Settlement gain (loss)	12,000,000
Qualified Plan | Post-retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	0	0
Qualified Plan | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	0	$ 250,000,000
Settlement gain (loss)	$ 11,000,000

Employee Benefit Plans - Schedu

Employee Benefit Plans - Schedule of Future Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2017USD ($)
Pension Plans
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2,018	$ 198
2,019	193
2,020	189
2,021	186
2,022	183
2023-2026	888
Total	1,837
Post-retirement Medical Plan
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2,018	38
2,019	28
2,020	26
2,021	24
2,022	22
2023-2026	76
Total	$ 214

Employee Benefit Plans - Sche70

Employee Benefit Plans - Schedule of Allocation of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 2,833	$ 2,539
Percent of Total Assets	100.00%	100.00%
Equity
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 2,060	$ 1,806
Percent of Total Assets	73.00%	71.00%
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 729	$ 665
Percent of Total Assets	26.00%	26.00%
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 44	$ 68
Percent of Total Assets	1.00%	3.00%

Employee Benefit Plans - Sche71

Employee Benefit Plans - Schedule of Changes in Benefit Obligation and Fair Value of Plan Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Change in Plan Assets:
Fair Value of Plan Assets at Beginning of Plan Year	$ 2,539,000,000
Employer Contributions	0	$ 250,000,000	$ 0
Fair Value of Plan Assets at End of Plan Year	2,833,000,000	2,539,000,000
Pension Plans
Actuarial Present Value of Benefit Obligation
Accumulated Benefit Obligation	2,873,000,000	2,717,000,000
Change in Projected Benefit Obligation:
Projected Benefit Obligation at Beginning of Plan Year	2,871,000,000	2,860,000,000
Service Cost	36,000,000	48,000,000	45,000,000
Interest Cost	92,000,000	119,000,000	116,000,000
Plan Participants' Contributions	0	0
Workforce Reduction Program/Curtailment	58,000,000	0
Actuarial Loss (Gain)	163,000,000	20,000,000
Benefits Paid	(218,000,000)	(176,000,000)
Benefit Obligation at End of Plan Year	3,002,000,000	2,871,000,000	2,860,000,000
Change in Plan Assets:
Fair Value of Plan Assets at Beginning of Plan Year	2,539,000,000	2,309,000,000
Actual Return on Plan Assets	467,000,000	139,000,000
Plan Participants' Contributions	0	0
Benefits Paid	(218,000,000)	(176,000,000)
Fair Value of Plan Assets at End of Plan Year	2,833,000,000	2,539,000,000	2,309,000,000
Funded Status at End of Plan Year	(169,000,000)	(332,000,000)
Curtailment gain (loss)	4,000,000
Pension Plans | Qualified Plan
Change in Plan Assets:
Employer Contributions	0	250,000,000
Pension Plans | Nonqualified Plan
Change in Plan Assets:
Employer Contributions	45,000,000	17,000,000
Post-retirement Benefits
Change in Projected Benefit Obligation:
Projected Benefit Obligation at Beginning of Plan Year	274,000,000	314,000,000
Service Cost	2,000,000	2,000,000	2,000,000
Interest Cost	7,000,000	12,000,000	12,000,000
Plan Participants' Contributions	7,000,000	6,000,000
Workforce Reduction Program/Curtailment	13,000,000	0
Actuarial Loss (Gain)	(17,000,000)	(22,000,000)
Benefits Paid	(36,000,000)	(38,000,000)
Benefit Obligation at End of Plan Year	250,000,000	274,000,000	314,000,000
Change in Plan Assets:
Fair Value of Plan Assets at Beginning of Plan Year	0	0
Actual Return on Plan Assets	0	0
Plan Participants' Contributions	7,000,000	6,000,000
Benefits Paid	(36,000,000)	(38,000,000)
Fair Value of Plan Assets at End of Plan Year	0	0	$ 0
Funded Status at End of Plan Year	(250,000,000)	(274,000,000)
Curtailment gain (loss)	13,000,000
Post-retirement Benefits | Qualified Plan
Change in Plan Assets:
Employer Contributions	0	0
Post-retirement Benefits | Nonqualified Plan
Change in Plan Assets:
Employer Contributions	$ 29,000,000	$ 32,000,000

Employee Benefit Plans - Sche72

Employee Benefit Plans - Schedule of Amount Recognized in Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Pension Plans
Amounts Recorded in Consolidated Balance Sheets [Abstract]
Long-term Assets	$ 57	$ 9
Current Liabilities	(15)	(15)
Long-term Liabilities	(211)	(326)
Net Amount Recognized in Consolidated Balance Sheets	(169)	(332)
Post-retirement Benefits
Amounts Recorded in Consolidated Balance Sheets [Abstract]
Long-term Assets	0	0
Current Liabilities	(38)	(39)
Long-term Liabilities	(212)	(235)
Net Amount Recognized in Consolidated Balance Sheets	$ (250)	$ (274)

Employee Benefit Plans - Benefi

Employee Benefit Plans - Benefit Obligations in Excess of Plan Assets (Details) $ in Millions	Dec. 31, 2017USD ($)
Projected Benefit Obligation
Aggregate Fair Value of Plan Assets	$ 0
Aggregate Projected Benefit Obligation	(226)
Accumulated Benefit Obligation
Aggregate Fair Value of Plan Assets	0
Aggregate Projected Benefit Obligation	$ (216)

Employee Benefit Plans - Sche74

Employee Benefit Plans - Schedule of Net Benefit Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Components of expense/ (income) related to net benefit expense [Abstract]
Special Termination Benefits - Workforce Reduction Program/Curtailment	$ 56
Pension Plans
Components of expense/ (income) related to net benefit expense [Abstract]
Service Cost	36	$ 48	$ 45
Interest Cost	92	119	116
Expected Return on Plan Assets	(171)	(157)	(162)
Amortization of Net Loss	41	48	70
Amortization of Prior Service Cost	0	0	0
Net Periodic Benefit Expense	(2)	58	69
Special Termination Benefits - Workforce Reduction Program/Curtailment	60	0	7
Settlement Loss (Gain)	11	(1)	(2)
Total Expense	69	57	74
Post-retirement Benefits
Components of expense/ (income) related to net benefit expense [Abstract]
Service Cost	2	2	2
Interest Cost	7	12	12
Expected Return on Plan Assets	0	0	0
Amortization of Net Loss	0	3	4
Amortization of Prior Service Cost	0	0	(1)
Net Periodic Benefit Expense	9	17	17
Special Termination Benefits - Workforce Reduction Program/Curtailment	13	0	0
Settlement Loss (Gain)	0	0	0
Total Expense	$ 22	$ 17	$ 17

Employee Benefit Plans - Sche75

Employee Benefit Plans - Schedule of Pre-tax Change in Other Comprehensive Loss (Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Pension Plans
Components of Other Comprehensive Loss (Income) [Abstract]
(Gains) Losses	$ (131)	$ 38
Expense (Income) recognized in the income statement
Amortization of net losses	41	48	$ 70
Settlement gain	11	(1)	(2)
Curtailment loss	4	0
Amortization of prior service costs	0	0	0
Estimated amount to be expensed in the future period	43
Post-retirement Benefits
Components of Other Comprehensive Loss (Income) [Abstract]
(Gains) Losses	(17)	(22)
Expense (Income) recognized in the income statement
Amortization of net losses	0	3	4
Settlement gain	0	0	0
Curtailment loss	0	0
Amortization of prior service costs	$ 0	$ 0	$ (1)

Employee Benefit Plans - Sche76

Employee Benefit Plans - Schedule of Weighted-Average Assumptions Used (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 30, 2016
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit Cost for Current Plan Year (as a percent)			6.75%	7.00%
Benefit Cost for Subsequent Plan Year (as a percent)		6.75%	6.75%	6.75%
Benefit Cost for Plan Year (as a percent)			0.00%	0.00%
Service Cost for Plan Year (as a percent)	4.35%	4.26%	4.26%	4.30%
Interest Cost for Plan Year (as a percent)	3.37%	3.26%	3.26%	4.30%
Benefit Obligation at End of Plan Year (as a percent)		3.56%	3.56%	4.08%
Salary Scale Inflation (as a percent)			4.60%	4.60%
Post-retirement Medical Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit Cost for Plan Year (as a percent)			0.00%	0.00%
Service Cost for Plan Year (as a percent)	4.20%	4.11%	4.11%	3.85%
Interest Cost for Plan Year (as a percent)	2.88%	2.78%	2.78%	3.85%
Benefit Obligation at End of Plan Year (as a percent)		3.34%	3.34%	3.71%

Debt and Credit Agreements - Sc

Debt and Credit Agreements - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016
Debt Instrument [Line Items]
Subtotal Long-term Debt (including current portion)	$ 11,809	$ 11,293
Less Debt Due within One Year	(19)	(331)
Long-term Debt (excluding current portion)	$ 11,790	10,962
Notes
Debt Instrument [Line Items]
Average Interest Rates (as a percent)	4.30%
Subtotal Long-term Debt (including current portion)	$ 11,591	11,055
Equipment Obligations
Debt Instrument [Line Items]
Average Interest Rates (as a percent)	6.30%
Subtotal Long-term Debt (including current portion)	$ 213	232
Capital Leases
Debt Instrument [Line Items]
Average Interest Rates (as a percent)	16.20%
Subtotal Long-term Debt (including current portion)	$ 5	$ 6

Debt and Credit Agreements - Na

Debt and Credit Agreements - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	May 31, 2017	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Debt Instrument [Line Items]
Long-term Debt Issued		$ 850,000,000	$ 2,200,000,000	$ 1,200,000,000
Repayments of long-term debt		333,000,000	1,419,000,000	$ 229,000,000
Net increase in debt			800,000,000
Debt extinguishment expense			115,000,000
Repayments of debt			1,400,000,000
Notes due 2027
Debt Instrument [Line Items]
Long-term Debt Issued	$ 850,000,000
Notes issued, interest rate	3.25%
Notes due 2026 | Unsecured Debt
Debt Instrument [Line Items]
Face amount of debt issued			$ 700,000,000
Notes issued, interest rate			2.60%
Notes due 2046 | Unsecured Debt
Debt Instrument [Line Items]
Face amount of debt issued			$ 800,000,000
Notes issued, interest rate			3.80%
Notes due 2066 | Unsecured Debt
Debt Instrument [Line Items]
Face amount of debt issued			$ 700,000,000
Notes issued, interest rate			4.25%
Notes due May 1, 2017 | Unsecured Debt
Debt Instrument [Line Items]
Notes issued, interest rate			5.60%
Early redemption amount			$ 300,000,000
Notes due March 15, 2018 | Unsecured Debt
Debt Instrument [Line Items]
Notes issued, interest rate			6.25%
Early redemption amount			$ 600,000,000
Notes due February 1, 2019 | Unsecured Debt
Debt Instrument [Line Items]
Notes issued, interest rate			7.375%
Early redemption amount			$ 500,000,000
Unsecured Revolving Credit Facility, Current | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility capacity		1,000,000,000
Line of credit facility, amount outstanding		0
Accounts Receivable Securitization Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility capacity		200,000,000
Line of credit facility, amount outstanding		$ 0
Line of credit facility, total expiration period		3 years

Debt and Credit Agreements - 79

Debt and Credit Agreements - Schedule of Long-term Debt Maturities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Maturities of Long-term Debt [Abstract]
2,018	$ 19	$ 331
2,019	18
2,020	745
2,021	371
2,022	162
Thereafter	10,494
Total Long-term Debt Maturities, including current portion	$ 11,809

Other Income - Net (Details)

Other Income - Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Other Income and Expenses [Abstract]
Interest Income	$ 13	$ 10	$ 6
Income from Non-operating Real Estate Activities	0	27	83
Miscellaneous Income (Expense)	8	9	9
Total Other Income (Expense) - Net	21	46	98
Gross Revenue from Real Estate Operations included above	$ 0	$ 56	$ 104

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2018	Dec. 22, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015	Dec. 26, 2014
Operating Loss Carryforwards [Line Items]
Earnings before income taxes				$ 3,142	$ 2,741	$ 3,138
Non-cash credit to income tax expense			$ 3,600	$ (3,506)	0	0
Non-cash credit to income tax expense amount per share		$ 3.81	$ 3.91
U.S. corporate tax rate (as a percent)				35.00%
Income tax adjustment				$ 21
State income taxes expense (benefit)				(102)	(83)	(86)
Unrecognized tax benefits			$ 24	24	25	23	$ 21
Amount of unrecognized tax benefits that may favorably effect the effective income tax rate			19	19	16	15
Income Tax Uncertainties [Abstract]
Reduction (Increase) to income tax reserves due to interest and penalties of prior year tax positions			3	3	2	2
Previously recorded liabilities for interest and penalties of prior period tax positions			$ 6	6	6	$ 4
Federal and State Legislative
Operating Loss Carryforwards [Line Items]
Income tax adjustment					10
State income taxes expense (benefit)				$ 7	$ 4
Affiliated Entity
Operating Loss Carryforwards [Line Items]
Non-cash credit to income tax expense		$ 142
Non-cash credit to income tax expense amount per share		$ 0.10
Subsequent Event
Operating Loss Carryforwards [Line Items]
U.S. corporate tax rate (as a percent)	21.00%

Income Taxes - Schedule of Brea

Income Taxes - Schedule of Breakdown of Income Tax Expense Between Current and Deferred (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Current:
Federal	$ 787	$ 540	$ 619
State	117	82	95
Subtotal Current	904	622	714
Deferred:
Federal	(3,277)	355	414
State	44	50	42
Subtotal Deferred	(3,233)	405	456
Income Tax Expense	$ (2,329)	$ 1,027	$ 1,170

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Tax Expense Reconciled to Tax Computed at Statutory Rates (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Reconciliation between the statutory income tax rate and the effective income tax rate [Abstract]
Federal Income Taxes		$ 1,100	$ 959	$ 1,098
State Income Taxes		102	83	86
Other		(25)	(15)	(14)
Income Tax Expense		$ (2,329)	$ 1,027	$ 1,170
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal Income Taxes		35.00%	35.00%	35.00%
State Income Taxes		3.20%	3.00%	2.70%
Other		(0.80%)	(0.50%)	(0.40%)
Income Tax Rate		(74.20%)	37.50%	37.30%
Effect of change in enacted tax rate	$ 3,600	$ (3,506)	$ 0	$ 0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent		(111.60%)	0.00%	0.00%

Income Taxes - Schedule of Sign

Income Taxes - Schedule of Significant Components of Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Components of Deferred Tax Assets [Abstract]
Pension Plans	$ 41	$ 125
Other Employee Benefit Plans	182	272
Other	657	225
Total	880	622
Components of Deferred Tax Liabilities [Abstract]
Accelerated Depreciation	6,576	9,925
Other	722	293
Total	7,298	10,218
Net Deferred Income Tax Liabilities	$ 6,418	$ 9,596

Income Taxes - Schedule of Chan

Income Taxes - Schedule of Change to Total Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of the year	$ 25	$ 23	$ 21
Additions based on tax positions related to current year	1	1	1
Additions based on tax positions related to prior years	4	4	4
Reductions based on tax positions related to prior years	0	0	0
Settlements with taxing authorities, decrease in benefits	(4)	0
Settlements with taxing authorities, increase in benefits			1
Lapse of statute of limitations	(2)	(3)	(4)
Balance at end of the year	$ 24	$ 25	$ 23

Related Parties and Affiliate86

Related Parties and Affiliates - Narrative (Details) $ / shares in Units, $ in Millions	Dec. 22, 2017$ / shares	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2017USD ($)	Dec. 30, 2016USD ($)	Dec. 25, 2015USD ($)	Dec. 26, 2014note
Related Party Transaction [Line Items]
Effect of change in enacted tax rate		$ 3,600	$ (3,506)	$ 0	$ 0
Effect of change in tax rate (in dollars per share) | $ / shares	$ 3.81	$ 3.91
Corporate Joint Venture
Related Party Transaction [Line Items]
Difference between carrying amount and underlying equity		$ 347	347
Promissory notes executed | note						2
Interest expense			$ 6	$ 6
TTX Company
Related Party Transaction [Line Items]
Ownership percentage		20.00%	20.00%
Equity method investments		$ 626	$ 626
Voting interest in related party which is also an equity method investment | Corporate Joint Venture
Related Party Transaction [Line Items]
Ownership percentage		50.00%	50.00%
Economic interest in related party which is also an equity method investment | Corporate Joint Venture
Related Party Transaction [Line Items]
Ownership percentage		42.00%	42.00%

Related Parties and Affiliate87

Related Parties and Affiliates - Schedule of Minimum Rentals and Commitments under Operating Leases (Details) $ in Millions	Dec. 31, 2017USD ($)
Related Party Transaction [Line Items]
2,018	$ 68
2,019	64
2,020	50
2,021	45
2,022	41
Thereafter	128
Total	396
Corporate Joint Venture
Related Party Transaction [Line Items]
2,018	27
2,019	27
2,020	27
2,021	27
2,022	27
Thereafter	48
Total	$ 183

Related Parties and Affiliate88

Related Parties and Affiliates - Schedule of Related Party in the Consolidated Income Statement Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Related Party Amounts Consolidated Income Statements [Abstract]
Equity Earnings of Affiliates	$ (219)	$ (50)	$ (40)
Corporate Joint Venture | Materials, Supplies and Other
Related Party Amounts Consolidated Income Statements [Abstract]
Rents, fees and services	120	114	123
Purchase price amortization and other	4	4	4
Equity Earnings of Affiliates	(58)	(37)	(33)
Total	66	81	94
TTX Company | Materials, Supplies and Other
Related Party Amounts Consolidated Income Statements [Abstract]
Car hire rents	237	233	218
Equity Earnings of Affiliates	(157)	(26)	(20)
Total	$ 80	$ 207	$ 198

Related Parties and Affiliate89

Related Parties and Affiliates - Schedule of Related Party Consolidated Balance Sheet Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016
Related Party Transaction [Line Items]
Payable to Affiliates	$ 0	$ 0
Corporate Joint Venture | Accounts Payable
Related Party Transaction [Line Items]
Payable to Affiliates	123	91
Corporate Joint Venture | Long-term Debt | 2.89% CSX promissory note due October 2044
Related Party Transaction [Line Items]
Promissory notes payable to Conrail subsidiary	$ 73	73
Related party note, interest rate (as a percent)	2.89%
Corporate Joint Venture | Long-term Debt | 2.89% CSXT promissory note due October 2044
Related Party Transaction [Line Items]
Promissory notes payable to Conrail subsidiary	$ 151	151
Related party note, interest rate (as a percent)	2.89%
TTX Company | Accounts Payable
Related Party Transaction [Line Items]
Payable to Affiliates	$ 43	$ 47

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment committee equity target allocation percentage of pension assets	70.00%
Fixed Income
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment committee equity target allocation percentage of pension assets	30.00%
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized cost basis of investments	$ 91	$ 500

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Investment Assets (Details) - Fair Value - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	$ 95	$ 500
Certificates of Deposit and Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	415
Corporate Bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	61	63
Government Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	34	22
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	0
Level 1 | Certificates of Deposit and Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	0
Level 1 | Corporate Bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	0
Level 1 | Government Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	95	500
Level 2 | Certificates of Deposit and Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	415
Level 2 | Corporate Bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	61	63
Level 2 | Government Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	34	22
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	0
Level 3 | Certificates of Deposit and Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	0
Level 3 | Corporate Bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	0	0
Level 3 | Government Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	$ 0	$ 0

Fair Value Measurements - Sch92

Fair Value Measurements - Schedule of Investment Maturities (Details) - Fair Value - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Less than 1 year	$ 18	$ 417
1 - 2 years	3	12
2 - 5 years	8	4
Greater than 5 years	66	67
Investments at fair value	$ 95	$ 500

Fair Value Measurements - Sch93

Fair Value Measurements - Schedule of Fair Value and Carrying Value of Long-term Debt (Details) - Level 2 - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt (Including Current Maturities)	$ 13,220	$ 12,096
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt (Including Current Maturities)	$ 11,809	$ 11,293

Fair Value Measurements - Sch94

Fair Value Measurements - Schedule of Pension Plan Assets at Fair Value by Level (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	$ 2,833	$ 2,539
Total investments in the fair value hierarchy	1,764	1,616
Investments measured at net asset value	1,069	923
Equity
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2,060	1,806
Common Stock
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	1,022	940
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	729	665
Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	14	12
Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2	1
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	537	497
Government Securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	169	141
Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	9	14
Derivatives and other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	11	11
Level 1
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	1,038	953
Total investments in the fair value hierarchy	1,038	953
Level 1 | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	1,022	940
Level 1 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	14	12
Level 1 | Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2	1
Level 1 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 1 | Government Securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 1 | Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 1 | Derivatives and other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	726	663
Total investments in the fair value hierarchy	726	663
Level 2 | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 2 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 2 | Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 2 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	537	497
Level 2 | Government Securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	169	141
Level 2 | Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	9	14
Level 2 | Derivatives and other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	11	11
Level 3
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Total investments in the fair value hierarchy	0	0
Level 3 | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 3 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 3 | Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 3 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 3 | Government Securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 3 | Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 3 | Derivatives and other
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	$ 0	$ 0

Other Comprehensive Income _ 95

Other Comprehensive Income / (Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Comprehensive earnings		$ 5,625	$ 1,739	$ 1,969
Other Comprehensive Income (Loss):
(Loss) Income Before Reclassifications		161	(13)	(61)
Amounts Reclassified to Net Earnings		58	51	69
Tax (Expense) Benefit		(65)	(13)	(7)
Total Other Comprehensive Income		154	25	1
Pension and Other Post-Employment Benefits
Other Comprehensive Income (Loss):
Beginning Balance		(580)	(601)	(611)
(Loss) Income Before Reclassifications		148	(16)	(53)
Amounts Reclassified to Net Earnings		56	50	71
Tax (Expense) Benefit		(64)	(13)	(8)
Total Other Comprehensive Income		140	21	10
Ending Balance		(440)	(580)	(601)
Other
Other Comprehensive Income (Loss):
Beginning Balance		(60)	(64)	(55)
(Loss) Income Before Reclassifications		13	3	(8)
Amounts Reclassified to Net Earnings		2	1	(2)
Tax (Expense) Benefit		(1)	0	1
Total Other Comprehensive Income		14	4	(9)
Ending Balance		(46)	(60)	(64)
Accumulated Other Comprehensive Income (Loss)
Other Comprehensive Income (Loss):
Beginning Balance		(640)	(665)	(666)
Tax (Expense) Benefit		(162)	(335)	(347)
Total Other Comprehensive Income	[1]	154	25	1
Ending Balance		$ (486)	$ (640)	$ (665)
[1]	Accumulated Other Comprehensive Loss year-end balances shown above are net of tax. The associated taxes were $162 million, $335 million and $347 million for 2017, 2016 and 2015, respectively. For additional information see Note 14, Other Comprehensive Income.

Quarterly Financial Data (Una96

Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2018	Dec. 22, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Selected Quarterly Financial Information [Abstract]
Revenue			$ 2,863	$ 2,743	$ 2,933	$ 2,869	$ 3,037	$ 2,710	$ 2,704	$ 2,618	$ 11,408	$ 11,069	$ 11,811
Operating Income			1,121	876	958	712	1,004	841	840	704	3,667	3,389	3,584
Net Earnings			$ 4,140	$ 459	$ 510	$ 362	$ 458	$ 455	$ 445	$ 356	$ 5,471	$ 1,714	$ 1,968
Earnings Per Share, Basic (in dollars per share)			$ 4.63	$ 0.51	$ 0.55	$ 0.39	$ 0.49	$ 0.48	$ 0.47	$ 0.37	$ 6.01	$ 1.81	$ 2
Earnings Per Share, Assuming Dilution (in dollars per share)			$ 4.62	$ 0.51	$ 0.55	$ 0.39	$ 0.49	$ 0.48	$ 0.47	$ 0.37	$ 5.99	$ 1.81	$ 2
Effect of change in enacted tax rate			$ 3,600								$ (3,506)	$ 0	$ 0
Effect of change in tax rate (in dollars per share)		$ 3.81	$ 3.91
U.S. corporate tax rate (as a percent)											35.00%
Subsequent Event
Selected Quarterly Financial Information [Abstract]
U.S. corporate tax rate (as a percent)	21.00%

Summarized Consolidating Fina97

Summarized Consolidating Financial Data (Consolidating Income Statement) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Consolidated Income Statement
Revenue	$ 2,863	$ 2,743	$ 2,933	$ 2,869	$ 3,037	$ 2,710	$ 2,704	$ 2,618	$ 11,408	$ 11,069	$ 11,811
Expense									7,741	7,680	8,227
Operating Income	1,121	876	958	712	1,004	841	840	704	3,667	3,389	3,584
Equity in Earnings of Subsidiaries									0	0	0
Interest Expense									(546)	(579)	(544)
Other Income - Net									21	(69)	98
Earnings Before Income Taxes									3,142	2,741	3,138
Income Tax Benefit									2,329	(1,027)	(1,170)
Net Earnings	$ 4,140	$ 459	$ 510	$ 362	$ 458	$ 455	$ 445	$ 356	5,471	1,714	1,968
Total Comprehensive Earnings									5,625	1,739	1,969
Eliminations and Other
Consolidated Income Statement
Revenue									74	78	78
Expense									(171)	(155)	(106)
Operating Income									245	233	184
Equity in Earnings of Subsidiaries									(5,810)	(1,999)	(1,949)
Interest Expense									65	39	28
Other Income - Net									(28)	(1)	(9)
Earnings Before Income Taxes									(5,528)	(1,728)	(1,746)
Income Tax Benefit									4	(93)	(60)
Net Earnings									(5,524)	(1,821)	(1,806)
Total Comprehensive Earnings									(5,538)	(1,833)	(1,806)
CSX Corporation
Consolidated Income Statement
Revenue									0	0	0
Expense									(158)	(265)	(589)
Operating Income									158	265	589
Equity in Earnings of Subsidiaries									5,810	1,997	1,949
Interest Expense									(582)	(583)	(539)
Other Income - Net									7	(112)	(4)
Earnings Before Income Taxes									5,393	1,567	1,995
Income Tax Benefit									78	147	(27)
Net Earnings									5,471	1,714	1,968
Total Comprehensive Earnings									5,625	1,739	1,969
CSX Transportation
Consolidated Income Statement
Revenue									11,334	10,991	11,733
Expense									8,070	8,100	8,922
Operating Income									3,264	2,891	2,811
Equity in Earnings of Subsidiaries									0	2	0
Interest Expense									(29)	(35)	(33)
Other Income - Net									42	44	111
Earnings Before Income Taxes									3,277	2,902	2,889
Income Tax Benefit									2,247	(1,081)	(1,083)
Net Earnings									5,524	1,821	1,806
Total Comprehensive Earnings									$ 5,538	$ 1,833	$ 1,806

Summarized Consolidating Fina98

Summarized Consolidating Financial Data (Consolidating Balance Sheets) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015	Dec. 26, 2014
Current Assets:
Cash and Cash Equivalents	$ 401	$ 603	$ 628	$ 669
Short-term Investments	18	417
Accounts Receivable - Net	970	938
Receivable from Affiliates	0	0
Materials and Supplies	372	407
Other Current Assets	154	122
Total Current Assets	1,915	2,487
Properties	44,324	43,227
Accumulated Depreciation	(12,560)	(12,077)
Properties - Net	31,764	31,150
Other Long-term Assets	374	318
Total Assets	35,739	35,414
Current Liabilities:
Accounts Payable	847	806
Labor and Fringe Benefits Payable	602	545
Payable to Affiliates	0	0
Casualty, Environmental and Other Reserves	108	115
Current Maturities of Long-term Debt	19	331
Income and Other Taxes Payable	157	129
Other Current Liabilities	161	114
Total Current Liabilities	1,894	2,040
Casualty, Environmental and Other Reserves	266	259
Long-term Debt	11,790	10,962
Deferred Income Taxes - Net	6,418	9,596
Other Long-term Liabilities	650	863
Total Liabilities	21,018	23,720
Shareholders' Equity:
Common Stock, $1 Par Value	890	928
Other Capital	217	138
Retained Earnings	14,084	11,253
Accumulated Other Comprehensive Loss	(486)	(640)
Noncontrolling Minority Interest	16	15
Total Shareholders' Equity	14,721	11,694	11,668	11,176
Total Liabilities and Shareholders' Equity	$ 35,739	$ 35,414
Common stock par value (in dollars per share)	$ 1	$ 1
Investments in Conrail
Current Assets:
Investment in Affiliates, Subsidiaries and Other	$ 907	$ 840
Affiliates and Other Companies
Current Assets:
Investment in Affiliates, Subsidiaries and Other	779	619
Investment in Consolidated Subsidiaries
Current Assets:
Investment in Affiliates, Subsidiaries and Other	0	0
Eliminations and Other
Current Assets:
Cash and Cash Equivalents	6	17	9	59
Short-term Investments	18	2
Accounts Receivable - Net	670	721
Receivable from Affiliates	(4,743)	(3,508)
Materials and Supplies	0	0
Other Current Assets	10	16
Total Current Assets	(4,039)	(2,752)
Properties	2,844	2,708
Accumulated Depreciation	(1,542)	(1,442)
Properties - Net	1,302	1,266
Other Long-term Assets	(261)	(291)
Total Assets	(31,478)	(25,101)
Current Liabilities:
Accounts Payable	34	33
Labor and Fringe Benefits Payable	56	65
Payable to Affiliates	(5,344)	(3,957)
Casualty, Environmental and Other Reserves	13	13
Current Maturities of Long-term Debt	0	(1)
Income and Other Taxes Payable	28	16
Other Current Liabilities	3	2
Total Current Liabilities	(5,210)	(3,829)
Casualty, Environmental and Other Reserves	44	51
Long-term Debt	1	0
Deferred Income Taxes - Net	206	258
Other Long-term Liabilities	(314)	(330)
Total Liabilities	(5,273)	(3,850)
Shareholders' Equity:
Common Stock, $1 Par Value	(181)	(181)
Other Capital	(5,096)	(5,095)
Retained Earnings	(20,933)	(15,994)
Accumulated Other Comprehensive Loss	5	19
Noncontrolling Minority Interest	0	0
Total Shareholders' Equity	(26,205)	(21,251)
Total Liabilities and Shareholders' Equity	(31,478)	(25,101)
Eliminations and Other | Investments in Conrail
Current Assets:
Investment in Affiliates, Subsidiaries and Other	907	840
Eliminations and Other | Affiliates and Other Companies
Current Assets:
Investment in Affiliates, Subsidiaries and Other	18	15
Eliminations and Other | Investment in Consolidated Subsidiaries
Current Assets:
Investment in Affiliates, Subsidiaries and Other	(29,405)	(24,179)
CSX Corporation
Current Assets:
Cash and Cash Equivalents	274	305	444	510
Short-term Investments	0	415
Accounts Receivable - Net	(1)	2
Receivable from Affiliates	1,226	1,157
Materials and Supplies	0	0
Other Current Assets	(1)	0
Total Current Assets	1,498	1,879
Properties	1	1
Accumulated Depreciation	(1)	(1)
Properties - Net	0	0
Other Long-term Assets	39	2
Total Assets	30,903	26,021
Current Liabilities:
Accounts Payable	105	95
Labor and Fringe Benefits Payable	52	40
Payable to Affiliates	4,792	3,457
Casualty, Environmental and Other Reserves	0	0
Current Maturities of Long-term Debt	0	313
Income and Other Taxes Payable	(326)	(346)
Other Current Liabilities	5	0
Total Current Liabilities	4,628	3,559
Casualty, Environmental and Other Reserves	0	0
Long-term Debt	11,056	10,203
Deferred Income Taxes - Net	(130)	(203)
Other Long-term Liabilities	644	783
Total Liabilities	16,198	14,342
Shareholders' Equity:
Common Stock, $1 Par Value	890	928
Other Capital	217	138
Retained Earnings	14,084	11,253
Accumulated Other Comprehensive Loss	(486)	(640)
Noncontrolling Minority Interest	0	0
Total Shareholders' Equity	14,705	11,679
Total Liabilities and Shareholders' Equity	30,903	26,021
CSX Corporation | Investments in Conrail
Current Assets:
Investment in Affiliates, Subsidiaries and Other	0	0
CSX Corporation | Affiliates and Other Companies
Current Assets:
Investment in Affiliates, Subsidiaries and Other	(39)	(39)
CSX Corporation | Investment in Consolidated Subsidiaries
Current Assets:
Investment in Affiliates, Subsidiaries and Other	29,405	24,179
CSX Transportation
Current Assets:
Cash and Cash Equivalents	121	281	$ 175	$ 100
Short-term Investments	0	0
Accounts Receivable - Net	301	215
Receivable from Affiliates	3,517	2,351
Materials and Supplies	372	407
Other Current Assets	145	106
Total Current Assets	4,456	3,360
Properties	41,479	40,518
Accumulated Depreciation	(11,017)	(10,634)
Properties - Net	30,462	29,884
Other Long-term Assets	596	607
Total Assets	36,314	34,494
Current Liabilities:
Accounts Payable	708	678
Labor and Fringe Benefits Payable	494	440
Payable to Affiliates	552	500
Casualty, Environmental and Other Reserves	95	102
Current Maturities of Long-term Debt	19	19
Income and Other Taxes Payable	455	459
Other Current Liabilities	153	112
Total Current Liabilities	2,476	2,310
Casualty, Environmental and Other Reserves	222	208
Long-term Debt	733	759
Deferred Income Taxes - Net	6,342	9,541
Other Long-term Liabilities	320	410
Total Liabilities	10,093	13,228
Shareholders' Equity:
Common Stock, $1 Par Value	181	181
Other Capital	5,096	5,095
Retained Earnings	20,933	15,994
Accumulated Other Comprehensive Loss	(5)	(19)
Noncontrolling Minority Interest	16	15
Total Shareholders' Equity	26,221	21,266
Total Liabilities and Shareholders' Equity	36,314	34,494
CSX Transportation | Investments in Conrail
Current Assets:
Investment in Affiliates, Subsidiaries and Other	0	0
CSX Transportation | Affiliates and Other Companies
Current Assets:
Investment in Affiliates, Subsidiaries and Other	800	643
CSX Transportation | Investment in Consolidated Subsidiaries
Current Assets:
Investment in Affiliates, Subsidiaries and Other	$ 0	$ 0

Summarized Consolidating Fina99

Summarized Consolidating Financial Data (Consolidating Cash Flow Statements) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Operating Activities
Net Cash Provided by (Used in) Operating Activities	$ 3,472	$ 3,041	$ 3,370
Investing Activities
Property Additions	(2,040)	(2,398)	(2,562)
Purchase of Short-term Investments	(782)	(929)	(1,739)
Proceeds from Sales of Short-term Investments	1,193	1,325	1,225
Proceeds from Property Dispositions	97	195	147
Other Investing Activities	37	9	37
Net Cash Used in Investing Activities	(1,495)	(1,798)	(2,892)
Financing Activities
Long-term Debt Issued	850	2,200	1,200
Long-term Debt Repaid	(333)	(1,419)	(229)
Dividends Paid	(708)	(680)	(686)
Shares Repurchased	(1,970)	(1,056)	(804)
Other Financing Activities	(18)	(313)	0
Net Cash Used in Financing Activities	(2,179)	(1,268)	(519)
Net Decrease in Cash and Cash Equivalents	(202)	(25)	(41)
Cash and Cash Equivalents at Beginning of Period	603	628	669
Cash and Cash Equivalents at End of Period	401	603	628
Eliminations and Other
Operating Activities
Net Cash Provided by (Used in) Operating Activities	(359)	(362)	(587)
Investing Activities
Property Additions	(192)	(190)	(162)
Purchase of Short-term Investments	(8)	0	(5)
Proceeds from Sales of Short-term Investments	3	0	50
Proceeds from Property Dispositions	0	0	0
Other Investing Activities	(55)	(41)	(85)
Net Cash Used in Investing Activities	(252)	(231)	(202)
Financing Activities
Long-term Debt Issued	0	0	0
Long-term Debt Repaid	0	0	0
Dividends Paid	600	600	750
Shares Repurchased	0	0	0
Other Financing Activities	0	1	(11)
Net Cash Used in Financing Activities	600	601	739
Net Decrease in Cash and Cash Equivalents	(11)	8	(50)
Cash and Cash Equivalents at Beginning of Period	17	9	59
Cash and Cash Equivalents at End of Period	6	17	9
CSX Corporation
Operating Activities
Net Cash Provided by (Used in) Operating Activities	1,719	453	983
Investing Activities
Property Additions	0	0	0
Purchase of Short-term Investments	(774)	(929)	(1,734)
Proceeds from Sales of Short-term Investments	1,190	1,325	1,175
Proceeds from Property Dispositions	0	0	0
Other Investing Activities	(2)	(41)	(10)
Net Cash Used in Investing Activities	414	355	(569)
Financing Activities
Long-term Debt Issued	850	2,200	1,200
Long-term Debt Repaid	(313)	(1,400)	(200)
Dividends Paid	(708)	(680)	(686)
Shares Repurchased	(1,970)	(1,056)	(804)
Other Financing Activities	(23)	(11)	10
Net Cash Used in Financing Activities	(2,164)	(947)	(480)
Net Decrease in Cash and Cash Equivalents	(31)	(139)	(66)
Cash and Cash Equivalents at Beginning of Period	305	444	510
Cash and Cash Equivalents at End of Period	274	305	444
CSX Transportation
Operating Activities
Net Cash Provided by (Used in) Operating Activities	2,112	2,950	2,974
Investing Activities
Property Additions	(1,848)	(2,208)	(2,400)
Purchase of Short-term Investments	0	0	0
Proceeds from Sales of Short-term Investments	0	0	0
Proceeds from Property Dispositions	97	195	147
Other Investing Activities	94	91	132
Net Cash Used in Investing Activities	(1,657)	(1,922)	(2,121)
Financing Activities
Long-term Debt Issued	0	0	0
Long-term Debt Repaid	(20)	(19)	(29)
Dividends Paid	(600)	(600)	(750)
Shares Repurchased	0	0	0
Other Financing Activities	5	(303)	1
Net Cash Used in Financing Activities	(615)	(922)	(778)
Net Decrease in Cash and Cash Equivalents	(160)	106	75
Cash and Cash Equivalents at Beginning of Period	281	175	100
Cash and Cash Equivalents at End of Period	$ 121	$ 281	$ 175