Stock Plans and Share-Based Compensation (Long-term Incentive Plans) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended						0 Months Ended	12 Months Ended
	Dec. 27, 2013	Dec. 28, 2012	Dec. 30, 2011	Dec. 27, 2013 Long-term Incentive Plans [Member]	Dec. 28, 2012 Long-term Incentive Plans [Member]	Dec. 30, 2011 Long-term Incentive Plans [Member]	May 07, 2013 Performance Shares [Member] Two Thousand Thirteen Long-Term Incentive Plan (2013 LTIP) [Member]	Dec. 27, 2013 Performance Units [Member] Long-term Incentive Plans [Member] plan	Dec. 27, 2013 Restricted Stock Units (RSUs) [Member]	Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2013 [Member]		Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2013 [Member] Minimum [Member]	Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2013 [Member] Maximum [Member]	Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2014 [Member]		Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2014 [Member] Minimum [Member]	Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2014 [Member] Maximum [Member]	Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2015 [Member]		Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2015 [Member] Minimum [Member]	Dec. 27, 2013 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan - 2015 [Member] Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Grants With Performance Vesting, Operating Ratio							50.00%
Number of plans								3
Plan duration								3 years
Performance unit equivalent of CSX stock, in shares									1
Percentage of payout subject to reduction				(30.00%)
Total expense incurred due to long-term incentive plans	$ 14	$ 14	$ 30	$ 2	$ 3	$ 21
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Number of target units outstanding										1,080,000	[1]			1,340,000	[1]			1,318,000	[1]
Weighted-average fair value at grant date				$ 25.24	$ 21.97					$ 25.63	[1]			$ 22.13	[1]			$ 25.32	[1]
Payout Range												0.00%	200.00%			0.00%	200.00%			0.00%	200.00%
Percentage Of Grants With Performance Vesting, Return On Assets							50.00%

[1] Number of target units granted and weighted-average fair value calculations above include the value of both initial grants and subsequent, smaller grants issued at different prices based on grant date fair value to new or promoted employees not previously included.