Employee Benefit Plans (Tables)

12 Months Ended

Dec. 30, 2011

Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]

Schedule of summary of participants

The Company engages independent, external actuaries to compute the amounts of liabilities and expenses related to these plans subject to the assumptions that the Company selects. In order to perform this valuation, the actuaries are provided with the details of the population covered at the beginning of the year, summarized in the table below, and projects that population forward to the end of the year.

	Summary of Participants as of
	January 1, 2011
	Pension Plans	Post-retirement Medical Plan
Active Employees	4,879	2,827
Retirees and Beneficiaries	11,360	12,234
Other(a)	6,340	62
Total	22,579	15,123

(a) For pension plans, the other category consists mostly of terminated but vested former employees.  For post-retirement plans, the other category consists of employees on long-term disability that have not yet retired.

Schedule of future expected beneit payments

Future expected benefit payments are as follows:

	Expected Cash Flows
(Dollars in Millions)	Pension Benefits		Post-retirement Benefits
2012	$	170	$	42
2013	174		40
2014	175		38
2015	177		36
2016	181		35
2017-2020	917		146
Total	$	1,794	$	337

Schedule of allocation of plan assets

At December 2011, both the accumulated benefit obligation and the projected benefit obligation exceeded the plan assets of each pension plan. The distribution of pension plan assets as of the measurement date is shown in the table below, and these assets are netted against the pension liabilities on the balance sheet. The funded status, or amount by which the benefit obligation exceeds the fair value of plan assets, represents a liability. 

NOTE 8. Employee Benefit Plans, continued

	December 2011				December 2010
			Percent of				Percent of
(Dollars in Millions)	Amount		Total Assets		Amount		Total Assets
Equity	$	1,064	57	%	$	1,126	61	%
Fixed Income	755		41		717		39
Cash and Cash Equivalents	31		2		8		—
Total	$	1,850	100	%	$	1,851	100	%

Schedule of changes in benefit obligation and fair value of plan assets

Changes in benefit obligation and the fair value of plan assets for the 2011 and 2010 calendar plan years are as follows:

	Pension Benefits						Post-retirement Benefits
	Plan Year			Plan Year			Plan Year			Plan Year
(Dollars in Millions)	2011			2010			2011			2010
Actuarial Present Value of Benefit Obligation
Accumulated Benefit Obligation	$	2,516		$	2,354		N/A			N/A
Projected Benefit Obligation	2,668			2,487			$	388		$	383
Change in Projected Benefit Obligation:
Projected Benefit Obligation atBeginning of Plan Year	$	2,487		$	2,395		$	383		$	406
Service Cost	40			41			2			5
Interest Cost	121			122			11			20
Plan Participants' Contributions	—			—			7			16
Plan Amendments	—			(9		)	—			(6		)
Actuarial (Gain)/Loss	175			91			32			(11		)
Benefits Paid	(155		)	(153		)	(47		)	(47		)
Benefit Obligation at End of Plan Year	$	2,668		$	2,487		$	388		$	383
Change in Plan Assets:
Fair Value of Plan Assets at Beginning of Plan Year	$	1,851		$	1,781		$	—		$	—
Actual Return on Plan Assets	141			210			—			—
Non-qualified Employer Contributions	13			13			40			31
Plan Participants' Contributions	—			—			7			16
Benefits Paid	(155		)	(153		)	(47		)	(47		)
Fair Value of Plan Assets at End of Plan Year	$	1,850		$	1,851		—			—
Funded Status at End of Plan Year	$	(818	)	$	(636	)	$	(388	)	$	(383	)

Schedule of amount recognized in balance sheet

Amounts related to pension and post-retirement benefits recorded in labor and fringe benefits payable and other long-term liabilities on the balance sheet are as follows:

	Pension Benefits						Post-retirement Benefits
	December			December			December			December
(Dollars in Millions)	2011			2010			2011			2010
Amounts Recorded in Consolidated
Balance Sheets:
Current Liabilities	$	(15	)	$	(13	)	$	(42	)	$	(41	)
Long-term Liabilities	(803		)	(623		)	(346		)	(342		)
Net Amount Recognized in
Consolidated Balance Sheet	$	(818	)	$	(636	)	$	(388	)	$	(383	)

Schedule of net benefit expense

The following table describes the components of expense/(income) related to net benefit expense recorded in labor and fringe on the income statement.

	Pension Benefits Fiscal Years									Post-retirement Benefits Fiscal Years
(Dollars in Millions)	2011			2010			2009			2011			2010		2009
Service Cost	$	40		$	41		$	32		$	2		$	5	$	5
Interest Cost	121			122			129			11			20		25
Expected Return on Plan Assets	(157		)	(165		)	(154		)	—			—		—
Amortization of Net Loss	71			58			26			7			7		4
Amortization of Prior Service Cost	—			—			2			(1		)	—		—
Net Periodic Benefit Expense	$	75		$	56		$	35		$	19		$	32	$	34
Settlement Gain(a)	(2		)	(2		)	—			—			—		—
Total Expense	$	73		$	54		$	35		$	19		$	32	$	34

(a) In 2011 and 2010, in one of the company's pension plans, the lump-sum payments exceeded the sum of the service cost and interest cost recognized.  As such, the company was required to recognize a portion of its accumulated other comprehensive income related to that plan into earnings.

Schedule of pre-tax change in other comprehensive loss (income)

The following table shows the pre-tax change in other comprehensive loss (income) attributable to the components of net expense and the change in benefit obligation for CSX for pension and other post-employment benefits.

(Dollars in Millions)	Pension Benefits						Post-retirement Benefits
Components of Other Comprehensive	December			December			December			December
Loss (Income)	2011			2010			2011			2010
Recognized in the balance sheet
Losses (Gains)	$	191		$	48		$	25		$	(9	)
Prior service credits	$	—		$	(9	)	$	—		$	(6	)
Expense (Income) recognized in the income statement
Amortization of net losses (a)	$	71		$	58		$	7		$	7
Settlement gain	$	(2	)	$	(2	)	$	—		$	—
Amortization of prior service costs (b)	$	—		$	—		$	(1	)	$	—

(a) The estimated amount to be expensed for 2012 is $82 million and $9 million for pension benefits and post-retirement benefits, respectively. The increase in the pension expense is largely related to additional amortization of the losses incurred by the pension plan assets during 2011.

(b) Remaining prior service costs to be expensed in 2012 are less than $1 million. The estimated post-retirement benefits amount to be credited to expense for 2012 is $1 million.

Schedule of pre-tax amounts to be amortized that included in accumulated other comprehensive loss

As of December 30, 2011, the balances of pre-tax amounts to be amortized that are included in accumulated other comprehensive loss (a component of shareholders’ equity) are as follows:

	Pension Benefits		Post-retirement Benefits
Losses	$	1,169	$	102
Prior Service Costs (Credits)	1		(5		)
Total	$	1,170	$	97

Schedule of weighted-average assumptions used

Weighted-average assumptions used in accounting for the plans were as follows:

	Pension Benefits				Post-retirement Benefits
	2011		2010		2011		2010
Expected Long-term Return on Plan Assets:
Benefit Cost for Plan Year	8.25	%	8.50	%	N/A		N/A
Benefit Obligation at End of Plan Year	8.00	%	8.25	%	N/A		N/A
Discount Rates:
Benefit Cost for Plan Year	5.00	%	5.25	%	4.50	%	4.75	%
Benefit Obligation at End of Plan Year	4.75	%	5.00	%	4.25	%	4.50	%
Salary Scale Inflation	4.00	%	4.00	%	N/A		N/A

Schedule of health care cost trend rates

Additionally, there are cost differentials between Medicare and Non-Medicare eligible individuals which are reflected below.

	Post-retirement Benefits
	2011	2010
Health Care Cost Trend Rate:
Components of Benefit Cost:  Non-Medicare Eligible	8.5%	8.5%
Components of Benefit Cost:  Medicare Eligible	8.0%	8.0%
Benefit Obligations:  Non-Medicare Eligible	8.5%	8.5%
Benefit Obligations:  Medicare Eligible	8.0%	8.0%