| Pay vs Performance Disclosure - USD ($) | 12 Months Ended |
| Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 |
| Pay vs Performance Disclosure [Table] | | | |
| Pay vs Performance [Table Text Block] | Year (a) Summary Compensation Table Total for Current PEO (1) (b) Compensation Actually Paid to Current PEO (2) (c) Summary Compensation Table Total for Former PEO (1) (b1) Compensation Actually Paid to Former PEO (2) (c1) Average Summary Compensation Table Total for Non-PEO NEOs (1) (d) Average Compensation Actually Paid to Non-PEO NEOs (2) (e) Value of Initial Fixed $100 Investment Based On: Net Income (4) (in Millions) (h) CSX Cash Earnings (5) (in Millions) (i) Total Shareholder Return (f) Peer Group Total Shareholder Return (3) (g) 2022 $8,348,517 $9,301,674 $19,536,434 $9,694,786 $4,856,562 $3,422,243 $137 $128 $4,166 $2,955 2021 N/A N/A $20,006,806 $32,556,244 $4,076,812 $6,737,795 $160 $134 $3,781 $2,472 2020 N/A N/A $15,306,715 $28,736,814 $3,586,272 $6,163,283 $127 $111 $2,765 $1,761 | | |
| Company Selected Measure Name | Cash Earnings | | |
| Named Executive Officers, Footnote [Text Block] | This table reflects the amounts reported in the “Summary Compensation Table” for Joseph R. Hinrichs, our current PEO, and James M. Foote, our former PEO, for each of the years listed. The non-PEO NEOs for whom the average compensation is presented in this table are: (i) for fiscal 2022, Messrs. Pelkey, Boone, Boychuk and Fortune; (ii) for fiscal 2021, Messrs. Pelkey, Boone, Boychuk, Goldman and Wallace and Ms. Sorfleet; (iii) and for fiscal 2020, Messrs. Boone, Boychuk, Goldman and Wallace. | | |
| Adjustment To PEO Compensation, Footnote [Text Block] | (2) Compensation “actually paid” for the PEOs and average compensation “actually paid” for the non-PEO NEOs in 2022, 2021 and 2020 reflect the respective amounts set forth in columns (b), (b1) and (d), adjusted as follows in the table below, as determined in accordance with SEC rules. These dollar amounts do not reflect the actual amount of compensation earned by or paid to the PEO and our other NEOs during the applicable year. Calculation for Current PEO Calculation for Former PEO Calculation for Average of Calculation of Compensation “Actually Paid” Year 2020 ($) Year 2021 Year 2022 Year 2020 Year 2021 Year 2022 Year 2020 Year 2021 Year 2022 Summary Compensation Table Total N/A N/A 8,348,517 15,306,715 20,006,806 19,536,434 3,586,272 4,076,812 4,856,562 Less Stock Award Value Reported in Summary Compensation Table for the Covered Year N/A N/A (7,000,026) (11,996,569) (12,192,859) (12,893,118) (2,590,164) (2,359,343) (3,121,007) Plus Fair Value for Awards Granted in the Covered Year N/A N/A 7,953,183 15,823,776 17,440,890 11,220,663 3,505,606 3,329,128 2,736,407 Change in Fair Value of Awards from Prior Years that Vested in the Covered Year N/A N/A — 1,040,047 (137,809) (960,026) (160,466) (15,856) (108,100) Change in Fair Value of Outstanding Unvested Awards from Prior Years N/A N/A — 8,607,449 7,942,001 (6,885,373) 1,833,620 1,799,713 (876,674) Less Fair Value of Awards Forfeited during the Covered Year N/A N/A — — — — — — — Plus Fair Value of Incremental Dividends of Earnings Paid on Stock Awards N/A N/A — — — — — — — Less Aggregate Change in Actuarial Present Value of Accumulated Benefit Under Pension Plans N/A N/A — (338,576) (798,423) (704,454) (93,643) (168,385) (125,379) Plus Aggregate Service Cost and Prior Service Cost for Pension Plans N/A N/A — 293,972 295,638 380,660 82,057 75,725 60,434 Compensation “Actually Paid” N/A N/A 9,301,674 28,736,814 32,556,244 9,694,786 6,163,283 6,737,795 3,422,243 Fair values set forth in the table above are computed in accordance with ASC 718 as of the end of the respective fiscal year, other than fair values of awards that vest in the covered year, which are valued as of the applicable vesting date. | | |
| Non-PEO NEO Average Total Compensation Amount | $ 4,856,562 | $ 4,076,812 | $ 3,586,272 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 3,422,243 | 6,737,795 | 6,163,283 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | (2) Compensation “actually paid” for the PEOs and average compensation “actually paid” for the non-PEO NEOs in 2022, 2021 and 2020 reflect the respective amounts set forth in columns (b), (b1) and (d), adjusted as follows in the table below, as determined in accordance with SEC rules. These dollar amounts do not reflect the actual amount of compensation earned by or paid to the PEO and our other NEOs during the applicable year. Calculation for Current PEO Calculation for Former PEO Calculation for Average of Calculation of Compensation “Actually Paid” Year 2020 ($) Year 2021 Year 2022 Year 2020 Year 2021 Year 2022 Year 2020 Year 2021 Year 2022 Summary Compensation Table Total N/A N/A 8,348,517 15,306,715 20,006,806 19,536,434 3,586,272 4,076,812 4,856,562 Less Stock Award Value Reported in Summary Compensation Table for the Covered Year N/A N/A (7,000,026) (11,996,569) (12,192,859) (12,893,118) (2,590,164) (2,359,343) (3,121,007) Plus Fair Value for Awards Granted in the Covered Year N/A N/A 7,953,183 15,823,776 17,440,890 11,220,663 3,505,606 3,329,128 2,736,407 Change in Fair Value of Awards from Prior Years that Vested in the Covered Year N/A N/A — 1,040,047 (137,809) (960,026) (160,466) (15,856) (108,100) Change in Fair Value of Outstanding Unvested Awards from Prior Years N/A N/A — 8,607,449 7,942,001 (6,885,373) 1,833,620 1,799,713 (876,674) Less Fair Value of Awards Forfeited during the Covered Year N/A N/A — — — — — — — Plus Fair Value of Incremental Dividends of Earnings Paid on Stock Awards N/A N/A — — — — — — — Less Aggregate Change in Actuarial Present Value of Accumulated Benefit Under Pension Plans N/A N/A — (338,576) (798,423) (704,454) (93,643) (168,385) (125,379) Plus Aggregate Service Cost and Prior Service Cost for Pension Plans N/A N/A — 293,972 295,638 380,660 82,057 75,725 60,434 Compensation “Actually Paid” N/A N/A 9,301,674 28,736,814 32,556,244 9,694,786 6,163,283 6,737,795 3,422,243 Fair values set forth in the table above are computed in accordance with ASC 718 as of the end of the respective fiscal year, other than fair values of awards that vest in the covered year, which are valued as of the applicable vesting date. | | |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | The following chart sets forth the relationship between “Compensation Actually Paid” to our PEO, the average of “Compensation Actually Paid” to our other NEOs, the Company’s cumulative TSR and the peer group’s cumulative TSR over the three-year period from 2020 through 2022. The peer group TSR is based on the S&P 500 Industrials Index. | | |
| Compensation Actually Paid vs. Net Income [Text Block] | The following chart sets forth the relationship between “Compensation Actually Paid” to our PEO, the average of “Compensation Actually Paid” to our other NEOs and our net income during fiscal years 2020 through 2022. | | |
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | The following chart sets forth the relationship between “Compensation Actually Paid” to our PEO, the average of “Compensation Actually Paid” to our other NEOs and CSX Cash Earnings (CCE) during fiscal years 2020 through 2022. | | |
| Total Shareholder Return Vs Peer Group [Text Block] | The following chart sets forth the relationship between “Compensation Actually Paid” to our PEO, the average of “Compensation Actually Paid” to our other NEOs, the Company’s cumulative TSR and the peer group’s cumulative TSR over the three-year period from 2020 through 2022. The peer group TSR is based on the S&P 500 Industrials Index. | | |
| Tabular List [Table Text Block] | Most Important Performance Measures Importance to the Company Average Annual Operating n Measures the average increase in operating income for each year of the LTIP cycle n Aligns with the Company’s objective of profitable growth CSX Cash Earnings (CCE) n Measures the Company’s ability to grow operating income while remaining focused on cost control and asset utilization n Encourages investments in growth projects that earn more than an expected rate of return Relative Total Shareholder Return (Relative TSR) n Designed to appropriately align NEO payouts with share price performance relative to a transportation-related peer group Operating Income n Used to gauge the general health of the Company and to quantify operating profit margin n Aligns with the Company’s objective of profitable growth Operating Ratio n Key indicator of the Company’s efficiency n Encourages the Company to deliver results that grow the business while optimizing assets Initiative-Based n Measures the Company’s ability to gain additional business on the CSX network through growth with new and existing customers n Directly supports profitable growth by driving operating income Safety n Reinforces the critical importance on ensuring employees’ personal safety and the safety of fellow railroaders and upholding our commitment to protect customers’ freight and the communities in which we operate Trip Plan Compliance ( supplemental ) n Ensures the Company successfully executes the service plan for customers’ shipments based on our commitments n Focuses on reliable and accurate service for customers Fuel Efficiency ( supplemental ) n Indicates the Company’s fuel productivity over the distance traveled n Supports environmental stewardship by reducing carbon emissions | | |
| Total Shareholder Return Amount | $ 137 | 160 | 127 |
| Peer Group Total Shareholder Return Amount | 128 | 134 | 111 |
| Net Income (Loss) | $ 4,166,000,000 | $ 3,781,000,000 | $ 2,765,000,000 |
| Company Selected Measure Amount | 2,955,000,000 | 2,472,000,000 | 1,761,000,000 |
| PEO Name | Joseph R. Hinrichs | | |
| Additional 402(v) Disclosure [Text Block] | Peer Group Total Shareholder Return is based on the S&P 500 Industrials Index, which is a peer group disclosed in the CD&A section of this Proxy Statement used by CSX to help determine executive pay.Reflects “Net Income” in the Company’s Consolidated Statements of Income included in the Company’s Annual Reports on Form 10-K for each of the years ended December 31, 2022, 2021 and 2020. | | |
| Measure [Axis]: 1 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | CSX Cash Earnings (CCE) | | |
| Non-GAAP Measure Description [Text Block] | We determined CSX Cash Earnings (CCE) to be the “most important” financial performance measure used to link performance to “Compensation Actually Paid” to our PEO and other NEOs in fiscal 2022, in accordance with Item 402(v) of Regulation S-K. CCE is a cash-flow based measure that incentivizes strategic investments earning more than the required return. CCE equals CSX’s gross cash earnings (after-tax EBITDA) minus the required return on gross operating assets. | | |
| Measure [Axis]: 2 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Average Annual OperatingIncome Growth Rate Percentage | | |
| Measure [Axis]: 3 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Relative Total Shareholder Return (Relative TSR) | | |
| Measure [Axis]: 4 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Operating Income | | |
| Measure [Axis]: 5 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Operating Ratio | | |
| Measure [Axis]: 6 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Initiative-BasedRevenue Growth | | |
| Measure [Axis]: 7 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Safety | | |
| Measure [Axis]: 8 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Trip Plan Compliance (supplemental) | | |
| Measure [Axis]: 9 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Fuel Efficiency (supplemental) | | |
| Hinrichs [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| PEO Total Compensation Amount | $ 8,348,517 | | |
| PEO Actually Paid Compensation Amount | 9,301,674 | | |
| Foote [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| PEO Total Compensation Amount | 19,536,434 | $ 20,006,806 | $ 15,306,715 |
| PEO Actually Paid Compensation Amount | 9,694,786 | 32,556,244 | 28,736,814 |
| PEO [Member] | Hinrichs [Member] | Adjustment, Exclusion of Equity Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (7,000,026) | | |
| PEO [Member] | Hinrichs [Member] | Adjustment, Inclusion of Equity Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 7,953,183 | | |
| PEO [Member] | Hinrichs [Member] | Change in Fair Value for Vested Awards Granted in Prior Years [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | | |
| PEO [Member] | Hinrichs [Member] | Change in Fair Value for Unvested and Outstanding Awards Granted in Prior Years [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | | |
| PEO [Member] | Hinrichs [Member] | Adjustment, Exclusion of Awards Forfeited During Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | | |
| PEO [Member] | Hinrichs [Member] | Dividends Paid on Unvested Equity Awards During Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | | |
| PEO [Member] | Hinrichs [Member] | Aggregate Change in Actuarial Present Value of Pension Benefits [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | | |
| PEO [Member] | Hinrichs [Member] | Addition of Aggregate Service Cost and Prior Service Cost for Pension Plans [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | | |
| PEO [Member] | Foote [Member] | Adjustment, Exclusion of Equity Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (12,893,118) | (12,192,859) | (11,996,569) |
| PEO [Member] | Foote [Member] | Adjustment, Inclusion of Equity Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 11,220,663 | 17,440,890 | 15,823,776 |
| PEO [Member] | Foote [Member] | Change in Fair Value for Vested Awards Granted in Prior Years [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (960,026) | (137,809) | 1,040,047 |
| PEO [Member] | Foote [Member] | Change in Fair Value for Unvested and Outstanding Awards Granted in Prior Years [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (6,885,373) | 7,942,001 | 8,607,449 |
| PEO [Member] | Foote [Member] | Adjustment, Exclusion of Awards Forfeited During Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Foote [Member] | Dividends Paid on Unvested Equity Awards During Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Foote [Member] | Aggregate Change in Actuarial Present Value of Pension Benefits [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (704,454) | (798,423) | (338,576) |
| PEO [Member] | Foote [Member] | Addition of Aggregate Service Cost and Prior Service Cost for Pension Plans [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 380,660 | 295,638 | 293,972 |
| Non-PEO NEO [Member] | Adjustment, Exclusion of Equity Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (3,121,007) | (2,359,343) | (2,590,164) |
| Non-PEO NEO [Member] | Adjustment, Inclusion of Equity Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 2,736,407 | 3,329,128 | 3,505,606 |
| Non-PEO NEO [Member] | Change in Fair Value for Vested Awards Granted in Prior Years [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (108,100) | (15,856) | (160,466) |
| Non-PEO NEO [Member] | Change in Fair Value for Unvested and Outstanding Awards Granted in Prior Years [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (876,674) | 1,799,713 | 1,833,620 |
| Non-PEO NEO [Member] | Adjustment, Exclusion of Awards Forfeited During Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| Non-PEO NEO [Member] | Dividends Paid on Unvested Equity Awards During Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| Non-PEO NEO [Member] | Aggregate Change in Actuarial Present Value of Pension Benefits [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (125,379) | (168,385) | (93,643) |
| Non-PEO NEO [Member] | Addition of Aggregate Service Cost and Prior Service Cost for Pension Plans [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ 60,434 | $ 75,725 | $ 82,057 |
