Summarized Consolidating Balance Sheet (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010	Sep. 24, 2010	Dec. 25, 2009
Current Assets
Cash and Cash Equivalents	$ 580	$ 1,292	$ 636	$ 1,029
Short-term Investments	61	54
Accounts Receivable - Net	1,148	993
Receivable from Affiliates	0	0
Materials and Supplies	236	218
Deferred Income Taxes	164	192
Other Current Assets	112	106
Total Current Assets	2,301	2,855
Properties	33,141	32,065
Accumulated Depreciation	(8,723)	(8,266)
Properties - Net	24,418	23,799
Other Long-term Assets	361	353
Total Assets	28,248	28,141
Current Liabilities
Accounts Payable	1,170	1,046
Labor and Fringe Benefits Payable	474	520
Payable to Affiliates	0	0
Casualty, Environmental and Other Reserves	200	176
Current Maturities of Long-term Debt	494	613
Income and Other Taxes Payable	129	85
Other Current Liabilities	101	97
Total Current Liabilities	2,568	2,537
Casualty, Evironmental and Other Reserves	434	502
Long-term Debt	8,160	8,051
Deferred Income Taxes	7,535	7,053
Other Long-term Liabilities	1,283	1,298
Total Liabilities	19,980	19,441
Shareholders' Equity
Common Stock, $1 Par Value	1,050	370
Other Capital	0	0
Retained Earnings	7,944	9,087
Accumulated Other Comprehensive Loss	(738)	(771)
Noncontrolling Interest	12	14
Total Shareholders' Equity	8,268	8,700
Total Liabilities and Shareholders' Equity	28,248	28,141
Investments in Conrail | CSX Corporation
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	0	0
Affiliates and Other Companies | CSX Corporation
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	0	0
CSX Corporation
Current Assets
Cash and Cash Equivalents	367	1,100	463	918
Short-term Investments	0	0
Accounts Receivable - Net	5	5
Receivable from Affiliates	1,199	1,048
Materials and Supplies	0	0
Deferred Income Taxes	0	15
Other Current Assets	79	46
Total Current Assets	1,650	2,214
Properties	8	8
Accumulated Depreciation	(8)	(8)
Properties - Net	0	0
Other Long-term Assets	167	174
Total Assets	19,049	18,666
Current Liabilities
Accounts Payable	148	116
Labor and Fringe Benefits Payable	39	42
Payable to Affiliates	2,567	1,942
Casualty, Environmental and Other Reserves	0	0
Current Maturities of Long-term Debt	404	517
Income and Other Taxes Payable	529	378
Other Current Liabilities	0	0
Total Current Liabilities	3,687	2,995
Casualty, Evironmental and Other Reserves	0	0
Long-term Debt	7,008	6,815
Deferred Income Taxes	(583)	(526)
Other Long-term Liabilities	681	696
Total Liabilities	10,793	9,980
Shareholders' Equity
Common Stock, $1 Par Value	1,050	370
Other Capital	0	0
Retained Earnings	7,944	9,087
Accumulated Other Comprehensive Loss	(738)	(771)
Noncontrolling Interest	0	0
Total Shareholders' Equity	8,256	8,686
Total Liabilities and Shareholders' Equity	19,049	18,666
CSX Corporation | Investments in Consolidated Subsidiaries
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	17,232	16,278
Investments in Conrail | CSX Transportation
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	0	0
Affiliates and Other Companies | CSX Transportation
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	563	595
CSX Transportation
Current Assets
Cash and Cash Equivalents	140	118	111	30
Short-term Investments	0	0
Accounts Receivable - Net	446	447
Receivable from Affiliates	1,718	943
Materials and Supplies	236	218
Deferred Income Taxes	160	171
Other Current Assets	103	56
Total Current Assets	2,803	1,953
Properties	31,501	30,557
Accumulated Depreciation	(7,807)	(7,405)
Properties - Net	23,694	23,152
Other Long-term Assets	107	110
Total Assets	27,167	25,810
Current Liabilities
Accounts Payable	970	904
Labor and Fringe Benefits Payable	397	431
Payable to Affiliates	574	401
Casualty, Environmental and Other Reserves	186	161
Current Maturities of Long-term Debt	88	94
Income and Other Taxes Payable	124	109
Other Current Liabilities	101	96
Total Current Liabilities	2,440	2,196
Casualty, Evironmental and Other Reserves	352	411
Long-term Debt	1,151	1,235
Deferred Income Taxes	7,655	7,228
Other Long-term Liabilities	526	525
Total Liabilities	12,124	11,595
Shareholders' Equity
Common Stock, $1 Par Value	181	181
Other Capital	5,650	5,634
Retained Earnings	9,255	8,443
Accumulated Other Comprehensive Loss	(63)	(65)
Noncontrolling Interest	20	22
Total Shareholders' Equity	15,043	14,215
Total Liabilities and Shareholders' Equity	27,167	25,810
CSX Transportation | Investments in Consolidated Subsidiaries
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	0	0
Investments in Conrail | Eliminations
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	687	673
Affiliates and Other Companies | Eliminations
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	(82)	(134)
Eliminations
Current Assets
Cash and Cash Equivalents	73	74	62	81
Short-term Investments	61	54
Accounts Receivable - Net	697	541
Receivable from Affiliates	(2,917)	(1,991)
Materials and Supplies	0	0
Deferred Income Taxes	4	6
Other Current Assets	(70)	4
Total Current Assets	(2,152)	(1,312)
Properties	1,632	1,500
Accumulated Depreciation	(908)	(853)
Properties - Net	724	647
Other Long-term Assets	87	69
Total Assets	(17,968)	(16,335)
Current Liabilities
Accounts Payable	52	26
Labor and Fringe Benefits Payable	38	47
Payable to Affiliates	(3,141)	(2,343)
Casualty, Environmental and Other Reserves	14	15
Current Maturities of Long-term Debt	2	2
Income and Other Taxes Payable	(524)	(402)
Other Current Liabilities	0	1
Total Current Liabilities	(3,559)	(2,654)
Casualty, Evironmental and Other Reserves	82	91
Long-term Debt	1	1
Deferred Income Taxes	463	351
Other Long-term Liabilities	76	77
Total Liabilities	(2,937)	(2,134)
Shareholders' Equity
Common Stock, $1 Par Value	(181)	(181)
Other Capital	(5,650)	(5,634)
Retained Earnings	(9,255)	(8,443)
Accumulated Other Comprehensive Loss	63	65
Noncontrolling Interest	(8)	(8)
Total Shareholders' Equity	(15,031)	(14,201)
Total Liabilities and Shareholders' Equity	(17,968)	(16,335)
Eliminations | Investments in Consolidated Subsidiaries
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	(17,232)	(16,278)
Investments in Conrail
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	687	673
Affiliates and Other Companies
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	481	461
Investments in Consolidated Subsidiaries
Current Assets
Investment in Affiliates, Subsidiaries, and Joint Ventures	$ 0	$ 0