Employee Benefits (Contributions to Employee Benefit Plans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 28, 2014	Jun. 29, 2013	Dec. 28, 2013
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	$ 9	$ 5	$ 37	$ 36	$ 48
Total current year projected employer contributions			57
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	5	1	29	28	34
Total current year projected employer contributions			43
Nonpension Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	4	4	8	8	14
Total current year projected employer contributions			$ 14