Commitments and Contingencies - Schedule of Number of Locomotives and Payments under Long-term Maintenance Program (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($) locomotive	Dec. 31, 2018 USD ($) locomotive	Dec. 31, 2017 USD ($) locomotive
Commitments and Contingencies Disclosure [Abstract]
Amounts Paid \| $	$ 139	$ 170	$ 197
Number of Locomotives \| locomotive	1,897	1,910	2,062

Cost of maintenance incurred and directly related to good produced and service rendered.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(2))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Name:	us-gaap_CostMaintenance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration