Certain issued and outstanding junior subordinated notes pertaining to certain financial covenants.

No definition available.

Name:	bni_DebtInstrumentCovenantDebt
Namespace Prefix:	bni_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Remaining Debt Securities Authorized by the Board

+ References

No definition available.

+ Details

Name:	bni_RemainingDebtSecuritiesAuthorizedbytheBoard
Namespace Prefix:	bni_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

- 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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=bni_SECDebtShelfRegistrationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_JuniorSubordinatedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bni_ThreePointZeroFivePercentDueFebruary152051Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bni_ThreePointSixPercentDebentureDueSeptember12020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt Notes and Debentures (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 01, 2020	Apr. 30, 2020
SEC Debt Shelf Registration
Debt Instrument [Line Items]
Remaining Debt Securities Authorized by the Board	$ 1,100
Junior Subordinated Debt
Debt Instrument [Line Items]
Subordinated notes related to financial covenants	$ 500
Three Point Zero Five Percent Due February 15, 2051 \| Corporate Debt Securities
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 575
Debt Instrument, Interest Rate, Stated Percentage			3.05%
Three Point Six Percent Debenture Due September 1, 2020 \| Corporate Debt Securities
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 250
Debt Instrument, Interest Rate, Stated Percentage		3.60%