Employee Benefits (Contributions to Employee Benefit Plans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012	Dec. 29, 2012
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	$ 5	$ 8	$ 36	$ 33	$ 51
Total current year projected employer contributions	62		62
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	1	3	28	24	38
Total current year projected employer contributions	45		45
Nonpension Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	4	5	8	9	13
Total current year projected employer contributions	$ 17		$ 17