Summarized Consolidating Financial Data - Consolidating Balance Sheet (Details) - USD ($) $ / shares in Units, $ in Millions	Sep. 25, 2015	Dec. 26, 2014	Sep. 26, 2014	Dec. 27, 2013
Current Assets:
Cash and Cash Equivalents	$ 541	$ 669	$ 479	$ 592
Short-term Investments	425	292
Accounts Receivable - Net	1,003	1,129
Receivable from Affiliates	0	0
Materials and Supplies	309	273
Deferred Income Taxes	137	141
Other Current Assets	87	68
Total Current Assets	2,502	2,572
Properties	40,843	39,343
Accumulated Depreciation	(11,206)	(10,759)
Properties - Net	29,637	28,584
Other Long-term Assets	500	541
Total Assets	34,015	33,053
Current Liabilities:
Accounts Payable	842	845
Labor and Fringe Benefits Payable	447	613
Payable to Affiliates	0	0
Casualty, Environmental and Other Reserves	146	142
Current Maturities of Long-term Debt	18	228
Income and Other Taxes Payable	282	163
Other Current Liabilities	187	116
Total Current Liabilities	1,922	2,107
Casualty, Environmental and Other Reserves	270	276
Long-term Debt	10,088	9,514
Deferred Income Taxes	8,957	8,858
Other Long-term Liabilities	1,118	1,122
Total Liabilities	22,355	21,877
Shareholders' Equity
Common Stock, $1 Par Value	975	992
Other Capital	120	92
Retained Earnings	11,195	10,734
Accumulated Other Comprehensive Loss	(645)	(666)
Noncontrolling Interest	15	24
Total Shareholders' Equity	11,660	11,176
Total Liabilities and Shareholders' Equity	$ 34,015	$ 33,053
Common stock, par value (in dollars per share)	$ 1	$ 1
Investments in Conrail
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	$ 793	$ 779
Affiliates and Other Companies
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	583	577
Investments in Consolidated Subsidiaries
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	0	0
CSX Corporation
Current Assets:
Cash and Cash Equivalents	311	510	295	439
Short-term Investments	425	250
Accounts Receivable - Net	2	2
Receivable from Affiliates	1,224	1,211
Materials and Supplies	0	0
Deferred Income Taxes	10	3
Other Current Assets	4	0
Total Current Assets	1,976	1,976
Properties	1	1
Accumulated Depreciation	(1)	(1)
Properties - Net	0	0
Other Long-term Assets	173	178
Total Assets	24,577	23,685
Current Liabilities:
Accounts Payable	145	106
Labor and Fringe Benefits Payable	35	38
Payable to Affiliates	3,184	3,053
Casualty, Environmental and Other Reserves	0	0
Current Maturities of Long-term Debt	0	200
Income and Other Taxes Payable	(320)	(150)
Other Current Liabilities	0	0
Total Current Liabilities	3,044	3,247
Casualty, Environmental and Other Reserves	0	0
Long-term Debt	9,302	8,705
Deferred Income Taxes	(159)	(172)
Other Long-term Liabilities	745	753
Total Liabilities	12,932	12,533
Shareholders' Equity
Common Stock, $1 Par Value	975	992
Other Capital	120	92
Retained Earnings	11,195	10,734
Accumulated Other Comprehensive Loss	(645)	(666)
Noncontrolling Interest	0	0
Total Shareholders' Equity	11,645	11,152
Total Liabilities and Shareholders' Equity	24,577	23,685
CSX Corporation \| Investments in Conrail
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	0	0
CSX Corporation \| Affiliates and Other Companies
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	(39)	(39)
CSX Corporation \| Investments in Consolidated Subsidiaries
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	22,467	21,570
CSX Transportation
Current Assets:
Cash and Cash Equivalents	168	100	128	91
Short-term Investments	0	0
Accounts Receivable - Net	178	206
Receivable from Affiliates	2,304	2,418
Materials and Supplies	309	272
Deferred Income Taxes	128	139
Other Current Assets	70	61
Total Current Assets	3,157	3,196
Properties	38,278	36,888
Accumulated Depreciation	(9,861)	(9,516)
Properties - Net	28,417	27,372
Other Long-term Assets	398	387
Total Assets	32,622	31,599
Current Liabilities:
Accounts Payable	667	707
Labor and Fringe Benefits Payable	374	511
Payable to Affiliates	483	514
Casualty, Environmental and Other Reserves	130	126
Current Maturities of Long-term Debt	18	29
Income and Other Taxes Payable	581	293
Other Current Liabilities	185	111
Total Current Liabilities	2,438	2,291
Casualty, Environmental and Other Reserves	216	213
Long-term Debt	786	809
Deferred Income Taxes	8,901	8,827
Other Long-term Liabilities	493	487
Total Liabilities	12,834	12,627
Shareholders' Equity
Common Stock, $1 Par Value	181	181
Other Capital	5,090	5,077
Retained Earnings	14,532	13,717
Accumulated Other Comprehensive Loss	(34)	(31)
Noncontrolling Interest	19	28
Total Shareholders' Equity	19,788	18,972
Total Liabilities and Shareholders' Equity	32,622	31,599
CSX Transportation \| Investments in Conrail
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	0	0
CSX Transportation \| Affiliates and Other Companies
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	650	644
CSX Transportation \| Investments in Consolidated Subsidiaries
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	0	0
Eliminations and Other
Current Assets:
Cash and Cash Equivalents	62	59	$ 56	$ 62
Short-term Investments	0	42
Accounts Receivable - Net	823	921
Receivable from Affiliates	(3,528)	(3,629)
Materials and Supplies	0	1
Deferred Income Taxes	(1)	(1)
Other Current Assets	13	7
Total Current Assets	(2,631)	(2,600)
Properties	2,564	2,454
Accumulated Depreciation	(1,344)	(1,242)
Properties - Net	1,220	1,212
Other Long-term Assets	(71)	(24)
Total Assets	(23,184)	(22,231)
Current Liabilities:
Accounts Payable	30	32
Labor and Fringe Benefits Payable	38	64
Payable to Affiliates	(3,667)	(3,567)
Casualty, Environmental and Other Reserves	16	16
Current Maturities of Long-term Debt	0	(1)
Income and Other Taxes Payable	21	20
Other Current Liabilities	2	5
Total Current Liabilities	(3,560)	(3,431)
Casualty, Environmental and Other Reserves	54	63
Long-term Debt	0	0
Deferred Income Taxes	215	203
Other Long-term Liabilities	(120)	(118)
Total Liabilities	(3,411)	(3,283)
Shareholders' Equity
Common Stock, $1 Par Value	(181)	(181)
Other Capital	(5,090)	(5,077)
Retained Earnings	(14,532)	(13,717)
Accumulated Other Comprehensive Loss	34	31
Noncontrolling Interest	(4)	(4)
Total Shareholders' Equity	(19,773)	(18,948)
Total Liabilities and Shareholders' Equity	(23,184)	(22,231)
Eliminations and Other \| Investments in Conrail
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	793	779
Eliminations and Other \| Affiliates and Other Companies
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	(28)	(28)
Eliminations and Other \| Investments in Consolidated Subsidiaries
Current Assets:
Investment in Affiliates and Consolidated Subsidiaries	$ (22,467)	$ (21,570)

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Balance Type:	credit
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- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.