Commitments and Contingencies (Environmental Matters) (Details) - Environmental Litigation [Member]	1 Months Ended	12 Months Ended
Apr. 30, 2014 mi	Dec. 25, 2015 counterparty mi
Loss Contingencies [Line Items]
Number of miles pertaining to Passaic River tidal reach required to be studied by EPA		17
Number of potentially responsible parties in connection with environmental liability \| counterparty		55
Number of miles under study	8

Number Of Potentially Responsible Parties In Connection With Environmental Liabilities For Operations Conducted Near Passaic River

No definition available.

Name:	csx_NumberOfPotentiallyResponsiblePartiesInConnectionWithEnvironmentalLiabilitiesForOperationsConductedNearPassaicRiver
Namespace Prefix:	csx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration