XML 117 R90.htm IDEA: XBRL DOCUMENT
v3.20.4

Debt (Debt Redemption) (Narrative) (Details) - USD ($) $ in Millions |  |  | 3 Months Ended | 10 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | ---
Nov. 01, 2020 | Oct. 15, 2019 | Dec. 31, 2019 | Nov. 01, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Extinguishment of Debt [Line Items] |  |  |  |  |  |
Early extinguishment of debt |  |  |  |  | $ (2) | $ (85)
4.0% Notes Due 2021 [Member] |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |
Debt Instrument, Repurchase Date | Nov. 01, 2020 |  |  |  |  |
Interest rate on note | 4.00% |  |  | 4.00% |  |
Principal outstanding | $ 500 |  |  | $ 500 |  |
Redemption price percentage of principal amount |  |  |  | 100.00% |  |
6.125% Notes Due 2020 [Member] |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |
Debt Instrument, Repurchase Date |  | Oct. 15, 2019 |  |  |  |
Early extinguishment of debt |  |  | $ 2 |  |  |
Interest rate on note |  | 6.125% |  |  |  |
Principal outstanding |  | $ 163 |  |  |  |

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of principal amount of debt redeemed. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value amount of debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Date the debt instrument was repurchased, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchaseDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ExtinguishmentOfDebtLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=117329964&loc=d3e12355-112629 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=117329964&loc=d3e12317-112629 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details
Name: | us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=unp_NotesDue202140PercentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=unp_NotesDue20206125PercentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |