Commitments and Contingencies Insurance (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Cash and cash equivalents	$ 1,852	$ 1,984
Estimated insurance recoveries	250
Insurance recoveries	155
Commercial Paper, Bank Time Deposits, and Money Market Funds \| BNSF Insurance Company
Loss Contingencies [Line Items]
Cash and cash equivalents	$ 454	$ 492

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Carrying amount as of the balance sheet date of amounts expected to be recovered under the terms of insurance contracts.

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The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

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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.

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