Casualty, Environmental and Other Reserves (Loss Contingencies Roll Forward) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 27, 2013	Dec. 28, 2012	Dec. 30, 2011
Casualty Reserves [Member]
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	$ 325	$ 372	$ 375
Charged to Expense	54	51	68
Payments	(99)	(98)	(71)
Balance end of period	280	325	372
Environmental Reserves [Member]
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	88	83	107
Charged to Expense	48	35	23
Payments	(36)	(30)	(47)
Balance end of period	100	88	83
Other Reserves [Member]
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	64	64	59
Charged to Expense	38	36	41
Payments	(31)	(36)	(36)
Balance end of period	71	64	64
Casualty, Environmental and Other [Member]
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	477	519	541
Charged to Expense	140	122	132
Payments	(166)	(164)	(154)
Balance end of period	$ 451	$ 477	$ 519