Income Taxes Components of Deferred Tax Assets / (Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Components of Deferred Tax Assets and Liabilities [Line Items]
Deferred Tax Liabilities, Property and Equipment	$ (18,624)	$ (17,727)
Deferred Tax Liabilities, Hedging	(10)bni_DeferredTaxLiabilitiesHedging	(11)bni_DeferredTaxLiabilitiesHedging
Deferred Tax Liability, Pension and Retiree Health and Welfare	0	(13)
Deferred Tax Liabilities, Other	(353)us-gaap_DeferredTaxLiabilitiesOther	(347)us-gaap_DeferredTaxLiabilitiesOther
Deferred Tax Liabilities, Gross	(18,987)us-gaap_DeferredIncomeTaxLiabilities	(18,098)us-gaap_DeferredIncomeTaxLiabilities
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits	335	371
Deferred Tax Assets, Tax Deferred Expense, Casualty and environmental	307	273
Deferred Tax Asset, Tax Deferred Expense, Intangible Assets and Liabilities	132	190
Deferred Tax Assets, Tax Deferred Expense, Long-term Debt Fair Value Adjustment	117	141
Deferred Tax Asset, Deferred Tax Expense, Pension and Retiree Health and Welfare Benefits	202	0
Deferred Tax Assets, Other	248us-gaap_DeferredTaxAssetsOther	257us-gaap_DeferredTaxAssetsOther
Deferred Tax Assets, Gross	1,341us-gaap_DeferredTaxAssetsGross	1,232us-gaap_DeferredTaxAssetsGross
Deferred Tax Liabilities, Net	(17,646)us-gaap_DeferredTaxLiabilities	(16,866)us-gaap_DeferredTaxLiabilities
Deferred Tax Liabilities, Net, Noncurrent	(18,001)	(17,224)
Deferred Tax Assets, Net, Current	$ 355	$ 358

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Deferred Tax Asset, Deferred Tax Expense, Pension and Retiree Health and Welfare Benefits

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from long-term debt fair value adjustment under acquisition method accounting.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from intangible assets and liabilities.

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Amount of deferred tax liability attributable to taxable temporary differences from hedging activities.

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Amount of deferred tax liability attributable to taxable temporary differences from pension and retiree health and welfare.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences expected to be realized or consumed within one year or operating cycle, if longer.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from compensation and benefits costs.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from reserves and accruals.

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Amount of deferred tax liability attributable to taxable temporary differences net of deferred tax asset attributable to deductible temporary differences and carryforwards after valuation allowances.

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Amount of deferred tax liability attributable to taxable temporary differences, net of deferred tax asset attributable to deductible temporary differences and carryforwards net of valuation allowances expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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Amount of deferred tax liability attributable to taxable temporary differences not separately disclosed.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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