Properties - Narrative (Details)	12 Months Ended
	Dec. 30, 2016 USD ($) depreciable_asset_category	Dec. 25, 2015 USD ($)	Dec. 26, 2014 USD ($)	Dec. 27, 2013 USD ($)
Railroad Assets [Abstract]
Percentage of assets depreciated under the group-life method	86.00%
Total fixed assets	$ 43,227,000,000	$ 41,574,000,000
Abnormal gains and losses	115,000,000
Annual depreciation expense	$ 1,301,000,000	1,208,000,000	$ 1,151,000,000
Capital Expenditures [Abstract]
Percentage of labor costs relating to the deconstruction of old track (as a percent)	20.00%
Percentage of labor costs relating to the installation of new track (as a percent)	80.00%
Minimum
Railroad Assets [Abstract]
Number of depreciable asset categories for railroad assets | depreciable_asset_category	130
Ties
Railroad Assets [Abstract]
Total fixed assets	$ 5,368,000,000	$ 5,077,000,000
Number of depreciable asset categories for railroad assets | depreciable_asset_category	18
Estimated useful life	27 years	27 years
Total Equipment
Railroad Assets [Abstract]
Total fixed assets	$ 11,604,000,000	$ 11,108,000,000
Life studies, frequency period	3 years
Total Road
Railroad Assets [Abstract]
Total fixed assets	$ 28,824,000,000	27,564,000,000
Life studies, frequency period	6 years
Technology Equipment | Minimum
Railroad Assets [Abstract]
Estimated useful life	4 years
Abnormal gain (loss) on operating property
Railroad Assets [Abstract]
Abnormal gains and losses	$ 110,000,000		$ 23,000,000	$ 0
Reimbursement of Environmental Costs
Railroad Assets [Abstract]
Abnormal gains and losses	$ 5,000,000
Gain (loss) on non-operating property
Railroad Assets [Abstract]
Abnormal gains and losses		$ 59,000,000