| Document and Entity Information | 12 Months Ended |
| Dec. 31, 2022 | |
| Cover [Abstract] | |
| Document Type | DEF 14A |
| Amendment Flag | false |
| Entity Registrant Name | UNION PACIFIC CORP |
| Entity Central Index Key | 0000100885 |
| 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] | Pay versus Performance Disclosure The following table provides a summary of compensation actually paid, as defined by the SEC (CAP), to the principal executive officer (PEO), the average CAP for the other non-PEO named executive officers (Other NEOs), total shareholder return (TSR), net income and the Company-selected financial measure (CSM) of operating income for 2022, 2021 and 2020. Year Summary Compensation Table Total for PEO (a) Compensation Actually Paid to PEO (a) Average Summary Compensation Table Total for Non-PEO NEOs (a) Average Compensation Actually Paid to Non-PEO NEOs (a) Value of Initial Fixed $100 Investment Based On: Net Income (c) In Millions CSM: Operating Income (c) In Millions Company TSR Peer Group TSR (b) 2022 $14,326,072 $ 5,546,491 $2,690,886 $ $122 $128 $6,998 $9,917 2021 $14,523,819 $ 23,246,960 $3,188,100 $ 4,326,065 $145 $155 $6,523 $9,338 2020 $16,632,099 $ 14,075,218 $4,297,722 $ 5,491,165 $ 118 $ 117 $5,349 $7,834 (a) Our CEO Mr. Fritz served as our principal executive officer (PEO) for each year reported. The Other NEOs represent the following individuals for each of the years shown: Ms. Hamann, Ms. Whited, Mr. Rocker and Mr. Gehringer for 2022 and 2021; and Vincenzo J. Vena, our former Chief Operating Officer, Ms. Hamann, Ms. Whited and Mr. Rocker for 2020. (b) The peer group index is the Dow Jones Transportation Index, which is included in Item 5 of the Company’s Form 10-K for the year ended December 31, 2022. (c) Net income and operating income for 2022 reflect a $92 million one-time charge for the labor agreements reached with our labor unions. Net income and operating income for 2020 reflect a $278 million non-cash impairment charge related to our Brazos yard investment. (d) CAP is defined by the SEC to include not only actual take-home pay for the reported year, but also (i) the year-end value of equity awards granted during the reported year, and (ii) the change in the value of equity awards that were unvested at the end of the prior year, measured through the date such awards vested or were forfeited, or through the end of the reported fiscal year. To calculate CAP, the following amounts were deducted from and added to the applicable executives’ “total compensation” as reported in the Summary Compensation Table (SCT): PEO SCT Total to CAP Reconciliation: Year Summary Compensation Table Total for PEO Reported Value of Equity Awards (i) Equity Award Adjustments (ii) Reported Change in the Actuarial Present Value of Pension Benefits (iii) Pension Benefit Adjustments (iv) Compensation Actually Paid to PEO 2022 $14,326,072 ($ 12,000,163) $ 2,504,547 ($ 0) $716,035 $ 5,546,491 2021 $14,523,819 ($ 10,500,166) $18,510,398 ($ 47,311) $760,220 $ 23,246,960 2020 $16,632,099 ($10,500,105) $ 10,583,878 ($ 3,269,470) $628,816 $ 14,075,218 Average Non-PEO NEOs SCT Total to CAP Reconciliation: Year Average Summary Compensation Table Total for Non-PEO NEOs Average Reported Value of Equity Awards (i) Equity Award Adjustments (ii) Average Reported Change in the Actuarial Present Value of Pension Benefits (iii) Pension Benefit Adjustments (iv) Average Compensation Actually Paid to Non-PEO NEOs 2022 $2,690,886 ($ 1,812,770) $ 594,285 ($ 0) $1,060,772 $ 2021 $3,188,100 ($ 1,475,163) $2,409,395 ($ 367,668) $ 571,401 $ 4,326,065 2020 $4,297,722 ($ 2,087,623) $4,094,333 ($1,064,470) $ 251,203 $ 5,491,165 (i) The amounts included in this column are the grant date fair value of equity awards as reported in the “Stock Awards” and “Option Awards” columns in the SCT for each applicable year. (ii) The equity award adjustments for each applicable year reflect the year-over-year change in the fair value of equity awards as itemized in the table below. Fair Value of Equity Awards PEO Equity Award Adjustments Non-PEO NEOs Equity Award Adjustments 2020 2021 2022 2020 2021 2022 As of year-end for awards granted during the year $ 11,615,105 $ 12,578,359 $ 8,228,329 $ 2,576,000 $ 1,767,115 $ 1,242,989 As of vest date for awards granted during the year $ 0 $ 0 $ 0 $ 1,372,918 $ 0 $ 0 Increase (decrease) from prior FYE for awards that vested during the year $ 4,891 ($ 1,151,373 ($ 1,183,911) ($ 1,750) ($ ($ 116,387 Year-over-year increase (decrease) of unvested awards granted in prior years ($ 1,036,118) $ 7,083,412 ($ $ 147,165 $ 726,151 ($ Total Equity Award Adjustments $ 10,583,878 $ 18,510,398 $ 2,504,547 $ 4,094,333 $ 2,409,395 $ 594,285 (iii) The amounts included in this column are the change in the present actuarial value of the executives’ accumulated benefit under the Company’s pension plan as reported in “Change in Pension and Nonqualified Deferred Compensation Earnings” column of the SCT for each applicable year. (iv) The total pension benefit adjustments for each applicable year include the actuarially determined service cost for services rendered during the applicable year (the “service cost”). | ||
| Company Selected Measure Name | Operating Income | ||
| Named Executive Officers, Footnote [Text Block] | (a) Our CEO Mr. Fritz served as our principal executive officer (PEO) for each year reported. The Other NEOs represent the following individuals for each of the years shown: Ms. Hamann, Ms. Whited, Mr. Rocker and Mr. Gehringer for 2022 and 2021; and Vincenzo J. Vena, our former Chief Operating Officer, Ms. Hamann, Ms. Whited and Mr. Rocker for 2020. | ||
| Peer Group Issuers, Footnote [Text Block] | (b) The peer group index is the Dow Jones Transportation Index, which is included in Item 5 of the Company’s Form 10-K for the year ended December 31, 2022. | ||
| PEO Total Compensation Amount | $ 14,326,072 | $ 14,523,819 | $ 16,632,099 |
| PEO Actually Paid Compensation Amount | $ 5,546,491 | 23,246,960 | 14,075,218 |
| Adjustment To PEO Compensation, Footnote [Text Block] | (d) CAP is defined by the SEC to include not only actual take-home pay for the reported year, but also (i) the year-end value of equity awards granted during the reported year, and (ii) the change in the value of equity awards that were unvested at the end of the prior year, measured through the date such awards vested or were forfeited, or through the end of the reported fiscal year. To calculate CAP, the following amounts were deducted from and added to the applicable executives’ “total compensation” as reported in the Summary Compensation Table (SCT): PEO SCT Total to CAP Reconciliation: Year Summary Compensation Table Total for PEO Reported Value of Equity Awards (i) Equity Award Adjustments (ii) Reported Change in the Actuarial Present Value of Pension Benefits (iii) Pension Benefit Adjustments (iv) Compensation Actually Paid to PEO 2022 $14,326,072 ($ 12,000,163) $ 2,504,547 ($ 0) $716,035 $ 5,546,491 2021 $14,523,819 ($ 10,500,166) $18,510,398 ($ 47,311) $760,220 $ 23,246,960 2020 $16,632,099 ($10,500,105) $ 10,583,878 ($ 3,269,470) $628,816 $ 14,075,218 (i) The amounts included in this column are the grant date fair value of equity awards as reported in the “Stock Awards” and “Option Awards” columns in the SCT for each applicable year. (ii) The equity award adjustments for each applicable year reflect the year-over-year change in the fair value of equity awards as itemized in the table below. Fair Value of Equity Awards PEO Equity Award Adjustments Non-PEO NEOs Equity Award Adjustments 2020 2021 2022 2020 2021 2022 As of year-end for awards granted during the year $ 11,615,105 $ 12,578,359 $ 8,228,329 $ 2,576,000 $ 1,767,115 $ 1,242,989 As of vest date for awards granted during the year $ 0 $ 0 $ 0 $ 1,372,918 $ 0 $ 0 Increase (decrease) from prior FYE for awards that vested during the year $ 4,891 ($ 1,151,373 ($ 1,183,911) ($ 1,750) ($ ($ 116,387 Year-over-year increase (decrease) of unvested awards granted in prior years ($ 1,036,118) $ 7,083,412 ($ $ 147,165 $ 726,151 ($ Total Equity Award Adjustments $ 10,583,878 $ 18,510,398 $ 2,504,547 $ 4,094,333 $ 2,409,395 $ 594,285 (iii) The amounts included in this column are the change in the present actuarial value of the executives’ accumulated benefit under the Company’s pension plan as reported in “Change in Pension and Nonqualified Deferred Compensation Earnings” column of the SCT for each applicable year. (iv) The total pension benefit adjustments for each applicable year include the actuarially determined service cost for services rendered during the applicable year (the “service cost”). | ||
| Non-PEO NEO Average Total Compensation Amount | $ 2,690,886 | 3,188,100 | 4,297,722 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 2,533,173 | 4,326,065 | 5,491,165 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | (d) CAP is defined by the SEC to include not only actual take-home pay for the reported year, but also (i) the year-end value of equity awards granted during the reported year, and (ii) the change in the value of equity awards that were unvested at the end of the prior year, measured through the date such awards vested or were forfeited, or through the end of the reported fiscal year. To calculate CAP, the following amounts were deducted from and added to the applicable executives’ “total compensation” as reported in the Summary Compensation Table (SCT): Average Non-PEO NEOs SCT Total to CAP Reconciliation: Year Average Summary Compensation Table Total for Non-PEO NEOs Average Reported Value of Equity Awards (i) Equity Award Adjustments (ii) Average Reported Change in the Actuarial Present Value of Pension Benefits (iii) Pension Benefit Adjustments (iv) Average Compensation Actually Paid to Non-PEO NEOs 2022 $2,690,886 ($ 1,812,770) $ 594,285 ($ 0) $1,060,772 $ 2021 $3,188,100 ($ 1,475,163) $2,409,395 ($ 367,668) $ 571,401 $ 4,326,065 2020 $4,297,722 ($ 2,087,623) $4,094,333 ($1,064,470) $ 251,203 $ 5,491,165 (i) The amounts included in this column are the grant date fair value of equity awards as reported in the “Stock Awards” and “Option Awards” columns in the SCT for each applicable year. (ii) The equity award adjustments for each applicable year reflect the year-over-year change in the fair value of equity awards as itemized in the table below. Fair Value of Equity Awards PEO Equity Award Adjustments Non-PEO NEOs Equity Award Adjustments 2020 2021 2022 2020 2021 2022 As of year-end for awards granted during the year $ 11,615,105 $ 12,578,359 $ 8,228,329 $ 2,576,000 $ 1,767,115 $ 1,242,989 As of vest date for awards granted during the year $ 0 $ 0 $ 0 $ 1,372,918 $ 0 $ 0 Increase (decrease) from prior FYE for awards that vested during the year $ 4,891 ($ 1,151,373 ($ 1,183,911) ($ 1,750) ($ ($ 116,387 Year-over-year increase (decrease) of unvested awards granted in prior years ($ 1,036,118) $ 7,083,412 ($ $ 147,165 $ 726,151 ($ Total Equity Award Adjustments $ 10,583,878 $ 18,510,398 $ 2,504,547 $ 4,094,333 $ 2,409,395 $ 594,285 (iii) The amounts included in this column are the change in the present actuarial value of the executives’ accumulated benefit under the Company’s pension plan as reported in “Change in Pension and Nonqualified Deferred Compensation Earnings” column of the SCT for each applicable year. (iv) The total pension benefit adjustments for each applicable year include the actuarially determined service cost for services rendered during the applicable year (the “service cost”). | ||
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | CAP versus TSR As shown in the chart below, the PEO’s CAP and Other NEOs’ Average CAP amounts are directionally aligned with the Company’s TSR. This is due primarily to the Company’s use of equity incentives, the value of which moves in line with our TSR, in addition to the Company’s financial performance. The Other NEOs’ Average CAP in 2020 also reflects the compensation of a more senior executive who ceased to serve as one of the Other NEOs in 2021. | ||
| Compensation Actually Paid vs. Net Income [Text Block] | CAP versus Net Income The Company’s net income increased in 2021 and 2022 while the PEO and Other NEOs’ CAP has varied significantly each year. This is due in large part to the significant emphasis the Company places on equity incentives, the value of which are affected by our TSR. In addition, the Company does not use net income to determine compensation levels or incentive plan payouts. CAP versus Operating Income - Company-Selected Measure (CSM) Operating income and operating ratio (of which operating income is a component) are equally weighted financial measures used in our annual incentive plan, as described in our CD&A. In addition, performance stock units awarded to our NEOs are earned based one-third (1/3) on operating income growth (OIG). The Company’s operating income has steadily increased year-over-year, although its impact on the PEO’s and Other NEO’s CAP has been muted or offset by other performance measures and by changes in the Company’s stock price. | ||
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | CAP versus Net Income The Company’s net income increased in 2021 and 2022 while the PEO and Other NEOs’ CAP has varied significantly each year. This is due in large part to the significant emphasis the Company places on equity incentives, the value of which are affected by our TSR. In addition, the Company does not use net income to determine compensation levels or incentive plan payouts. CAP versus Operating Income - Company-Selected Measure (CSM) Operating income and operating ratio (of which operating income is a component) are equally weighted financial measures used in our annual incentive plan, as described in our CD&A. In addition, performance stock units awarded to our NEOs are earned based one-third (1/3) on operating income growth (OIG). The Company’s operating income has steadily increased year-over-year, although its impact on the PEO’s and Other NEO’s CAP has been muted or offset by other performance measures and by changes in the Company’s stock price. | ||
| Total Shareholder Return Vs Peer Group [Text Block] | TSR: Company versus Peer Group The following chart presents the cumulative total shareholder return, assuming reinvestment of dividends, over the three-year period for the Company (UNP) and the Dow Jones Transportation Index (DJ Trans). As the table demonstrates, the Company’s 3-year cumulative TSR is generally aligned with our peer group index. | ||
| Tabular List [Table Text Block] | Most Important Measures to Determine 2022 CAP Below lists the most important financial metrics used to link 2022 CAP to Company performance. Operating income, operating ratio and return on invested capital are further described in our CD&A within the sections titled “2022 Annual Incentive Plan” and “Long-Term Equity Incentive Compensation.” • Operating Income • Operating Ratio • Return on Invested Capital | ||
| Total Shareholder Return Amount | $ 122 | 145 | 118 |
| Peer Group Total Shareholder Return Amount | 128 | 155 | 117 |
| Net Income (Loss) | $ 6,998,000,000 | $ 6,523,000,000 | $ 5,349,000,000 |
| Company Selected Measure Amount | 9,917,000,000 | 9,338,000,000 | 7,834,000,000 |
| PEO Name | Mr. Fritz | Mr. Fritz | Mr. Fritz |
| Charges for labor agreements | $ 92,000,000 | ||
| Non-cash impairment charge | $ 278,000,000 | ||
| Measure [Axis]: 1 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Operating Income | ||
| Measure [Axis]: 2 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Operating Ratio | ||
| Measure [Axis]: 3 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Return on Invested Capital | ||
| PEO [Member] | Reported Value of Equity Awards [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | $ (12,000,163) | $ (10,500,166) | (10,500,105) |
| PEO [Member] | Equity Award Adjustments [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 2,504,547 | 18,510,398 | 10,583,878 |
| PEO [Member] | As of Year-end for Awards Granted During the Year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 8,228,329 | 12,578,359 | 11,615,105 |
| PEO [Member] | As of Vest Date for Awards Granted During the Year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Increase (Decrease) from Prior FYE for Awards that Vested During the Year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (1,183,911) | (1,151,373) | 4,891 |
| PEO [Member] | Year-Over-Year Increase (Decrease) of Unvested Awards Granted in Prior Years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (4,539,871) | 7,083,412 | (1,036,118) |
| PEO [Member] | Reported Change in the Actuarial Present Value of Pension Benefits [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 0 | (47,311) | (3,269,470) |
| PEO [Member] | Pension Benefit Adjustments [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 716,035 | 760,220 | 628,816 |
| Non-PEO NEO [Member] | Reported Value of Equity Awards [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (1,812,770) | (1,475,163) | (2,087,623) |
| Non-PEO NEO [Member] | Equity Award Adjustments [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 594,285 | 2,409,395 | 4,094,333 |
| Non-PEO NEO [Member] | As of Year-end for Awards Granted During the Year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 1,242,989 | 1,767,115 | 2,576,000 |
| Non-PEO NEO [Member] | As of Vest Date for Awards Granted During the Year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 0 | 0 | 1,372,918 |
| Non-PEO NEO [Member] | Increase (Decrease) from Prior FYE for Awards that Vested During the Year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (116,387) | (83,871) | (1,750) |
| Non-PEO NEO [Member] | Year-Over-Year Increase (Decrease) of Unvested Awards Granted in Prior Years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (532,317) | 726,151 | 147,165 |
| Non-PEO NEO [Member] | Reported Change in the Actuarial Present Value of Pension Benefits [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 0 | (367,668) | (1,064,470) |
| Non-PEO NEO [Member] | Pension Benefit Adjustments [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | $ 1,060,772 | $ 571,401 | $ 251,203 |
