Pensions and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 30, 2014	Mar. 31, 2013
Retirement Plans
Components of net periodic benefit cost
Service cost	$ 197	$ 206
Interest cost	257	228
Expected return on plan assets	(402)	(363)
Amortization of prior service cost (credit)	1	4
Recognized actuarial losses	113	168
Net periodic benefit cost	166	243
Other Benefit Plans
Components of net periodic benefit cost
Service cost	53	48
Interest cost	50	37
Expected return on plan assets	(2)	(1)
Amortization of prior service cost (credit)	(9)	(1)
Recognized actuarial losses	34	28
Net periodic benefit cost	$ 126	$ 111