Stock Plans and Share-Based Compensation (Long-term Incentive Plans) (Details) (USD $)	12 Months Ended						1 Months Ended	12 Months Ended
	Dec. 28, 2012	Dec. 30, 2011	Dec. 31, 2010	Dec. 28, 2012 Long-term Incentive Plans [Member]	Dec. 30, 2011 Long-term Incentive Plans [Member]	Dec. 31, 2010 Long-term Incentive Plans [Member]	Jan. 31, 2013 Long-term Incentive Plans [Member] Subsequent Event [Member]	Dec. 28, 2012 Long Term Incentive Plan Year One [Member]	Dec. 30, 2011 Long Term Incentive Plan Year One [Member]	Dec. 28, 2012 Long Term Incentive Plan Year Two [Member]	Dec. 30, 2011 Long Term Incentive Plan Year Two [Member]	Dec. 28, 2012 Long Term Incentive Plan Year Three [Member]	Dec. 30, 2011 Long Term Incentive Plan Year Three [Member]	Dec. 28, 2012 Restricted Stock [Member]		Dec. 30, 2011 Restricted Stock [Member]		Dec. 31, 2010 Restricted Stock [Member]		Dec. 28, 2012 Performance Units [Member] Long-term Incentive Plans [Member] plan	Dec. 28, 2012 Restricted Stock Units (RSUs) [Member]	Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long-term Incentive Plans [Member]	Dec. 30, 2011 Restricted Stock Units (RSUs) [Member] Long-term Incentive Plans [Member]	Dec. 31, 2010 Restricted Stock Units (RSUs) [Member] Long-term Incentive Plans [Member]	Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year One [Member]		Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year One [Member] Minimum [Member]	Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year One [Member] Maximum [Member]	Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year Two [Member]		Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year Two [Member] Minimum [Member]	Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year Two [Member] Maximum [Member]	Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year Three [Member]		Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year Three [Member] Minimum [Member]	Dec. 28, 2012 Restricted Stock Units (RSUs) [Member] Long Term Incentive Plan Year Three [Member] Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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	$ 14,000,000	$ 30,000,000	$ 62,000,000	$ 3,000,000	$ 21,000,000	$ 56,000,000								$ 9,000,000	[1]	$ 7,000,000	[1]	$ 4,000,000	[1]
Shares issued subsequent to year end as a result of achieving performance targets under the long-term incentive plan (in shares)							189,000
Time Based Restricted Stock Unit Granted To Key Member Of Management								38,000	41,000	65,000	1,111,000	1,325,000	0									433,000	361,000	402,000					361,000				433,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Number of target units outstanding														1,353,000	[1]	1,572,000	[1]	1,173,000	[1]						1,182,000	[2]			1,079,000	[2]			1,311,000	[2]
Weighted-average fair value at grant date				$ 21.80	$ 25.02									$ 21.38		$ 16.91		$ 13.67							$ 18.27	[2]			$ 25.67	[2]			$ 21.98	[2]
Payout Range																											0.00%	200.00%			0.00%	200.00%			0.00%	200.00%
Unrecognized compensation cost				$ 22,000,000										$ 14,000,000
Expected weighted average period of recognition for unrecognized compensation cost (in years)				2 years										2 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested, Units Outstanding, beginning balance								1,144,000	1,103,000	1,014,000	0	0	0	678,000		702,000
Granted, Units Outstanding								38,000	41,000	65,000	1,111,000	1,325,000	0									433,000	361,000	402,000					361,000				433,000
Forfeited, Units Outstanding								0	0	0	(97,000)	(14,000)	0
Vested, Units Outstanding								1,182,000		0		0
Unvested, Units Outstanding, ending balance								0	1,144,000	1,079,000	1,014,000	1,311,000	0	629,000		678,000		702,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested, Weighted-Average Fair Value at Grant Date, beginning balance				$ 22.05	$ 17.94									$ 20.93		$ 14.69
Granted, Weighted-Average Fair Value at Grant Date				$ 21.80	$ 25.02									$ 21.38		$ 16.91		$ 13.67							$ 18.27	[2]			$ 25.67	[2]			$ 21.98	[2]
Forfeited, Weighted-Average Fair Value at Grant Date				$ (22.08)	$ (25.71)
Vested, Weighted-Average Fair Value at Grant Date				$ 18.27
Unvested, Weighted-Average Fair Value at Grant Date, ending balance				$ 23.84	$ 22.05	$ 17.94								$ 22.48		$ 20.93		$ 14.69

[1] Time-based restricted stock units were granted to key members of management and executives under the respective Long-term Incentive Plans in the amount of 433,000, 361,000, and 402,000 in 2012, 2011, and 2010, respectively, as described below. These units vest over three years, therefore only a partial amount of expense was recognized in 2012, 2011, and 2010, respectively.

[2] 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.