Employee Benefits (Contributions to Employee Benefit Plans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 30, 2013	Mar. 31, 2012	Dec. 29, 2012
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	$ 31	$ 25	$ 51
Total current year projected employer contributions	62
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	27	21	38
Total current year projected employer contributions	45
Nonpension Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	4	4	13
Total current year projected employer contributions	$ 17