Employee Benefit Plans (Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended			12 Months Ended
	Mar. 29, 2013	Dec. 28, 2012	Dec. 27, 2013 Pension Plan, Defined Benefit [Member]	Dec. 27, 2013 Other Postretirement Benefit Plan, Defined Benefit [Member]	Dec. 27, 2013 Qualified Employer Contributions [Member] Pension Plan, Defined Benefit [Member]	Dec. 28, 2012 Qualified Employer Contributions [Member] Pension Plan, Defined Benefit [Member]	Dec. 27, 2013 Qualified Employer Contributions [Member] Other Postretirement Benefit Plan, Defined Benefit [Member]	Dec. 28, 2012 Qualified Employer Contributions [Member] Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions					$ 0	$ 275	$ 0	$ 0
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2014			167	38
2015			171	36
2016			173	34
2017			176	32
2018			179	31
2019-2023			910	126
Total			1,776	297
Defined Benefit Plan, Contributions By Employer, Required Minimum Amount		25
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	$ 0