Retirement Plans (Details 1) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans [Member]
Components of net periodic pension cost
Service cost	$ 58	$ 49	$ 40
Interest cost	89	86	83
Expected return on plan assets	(109)	(86)	(59)
Amortization of unrecognized net actuarial losses	47	48	65
Settlement loss	0	8	17
Net periodic benefit cost	85	105	146
Postretirement Medical Plan [Member]
Components of net periodic pension cost
Service cost	6	5	3
Interest cost	5	4	4
Expected return on plan assets	0	0	0
Amortization of unrecognized net actuarial losses	2	1	0
Settlement loss	0	0	0
Net periodic benefit cost	$ 13	$ 10	$ 7