Employee Benefit Plans, Components of Net Periodic Benefit Costs (Details) (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 benefit cost:
Service cost	$ 104	$ 88	$ 104
Interest cost	85	83	79
Expected return on plan assets	(112)	(112)	(108)
Amortization of:
Prior service cost (credit)	2	3	3
Net loss	12	2	10
Net periodic benefit cost before special charges	91	64	88
Special charges	4	8	7
Net periodic benefit cost	95	72	95
Other Postretirement Benefit Plans [Member]
Components of net periodic benefit cost:
Service cost	11	10	12
Interest cost	22	26	25
Expected return on plan assets	0	0	0
Amortization of:
Prior service cost (credit)	(23)	(20)	(19)
Net loss	2	4	6
Net periodic benefit cost before special charges	12	20	24
Special charges	4	0	1
Net periodic benefit cost	$ 16	$ 20	$ 25