Employee Benefits Schedule of Defined Benefit Plan Disclosures (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
As of January 1				$ 487
Noncurrent asset	(36)	(44)		(36)
Noncurrent liability	195	140		195
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	97	22
As of January 1	634	550	491
Service cost	12	11	11
Interest cost on benefit obligation	29	28	31
Participants’ contributions	0	0
Actuarial loss (gain)	69	42
Benefit payments	(26)	(22)
As of January 1	473	406		487
Unfunded position as of December 31	(147)	(77)
Defined Benefit Plan, Accumulated Benefit Obligation	566	503
Actual return on plan assets	14	59
Company contributions	26	30
Noncurrent asset	0	0
Current liability	0	0
Noncurrent liability	(147)	(77)
Amortization of net actuarial loss	(8)	(3)
Amortization of prior service cost	(1)	(1)
Total Amounts included in comprehensive income	88	18
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	276	188
Net actuarial loss	275	186
Prior service cost	1	2
Discount rate used to calculate benefit obligation	5.00%	5.47%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	3.71%	3.80%
Long-term rate of return on plan assets	8.25%	8.50%
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	(4)	1
As of January 1	75	79	77
Service cost	2	2	2
Interest cost on benefit obligation	4	4	4
Participants’ contributions	2	2
Actuarial loss (gain)	(5)	1
Benefit payments	(7)	(7)
As of January 1	16	19		27
Unfunded position as of December 31	(48)	(63)
Actual return on plan assets	0	1
Company contributions	16	1
Noncurrent asset	0	0
Current liability	0	0
Noncurrent liability	(48)	(63)
Amortization of net actuarial loss	(1)	(1)
Amortization of prior service cost	(1)	(1)
Total Amounts included in comprehensive income	(6)	(1)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	19	25
Net actuarial loss	15	20
Prior service cost	4	5
Discount rate used to calculate benefit obligation	3.76%	4.02%
Defined Benefit Plan Discount rate - upper range	4.90%	5.40%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	4.58%	4.83%
Long-term rate of return on plan assets	7.09%	6.44%
Non Qualified Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	2	0
As of January 1	27	25	27
Service cost	0	0	0
Interest cost on benefit obligation	1	1	2
Participants’ contributions	0	0
Actuarial loss (gain)	3	0
Benefit payments	(2)	(3)
As of January 1	19	20		17
Unfunded position as of December 31	(10)	(6)
Defined Benefit Plan, Accumulated Benefit Obligation	27	25
Actual return on plan assets	0	2
Company contributions	0	0
Noncurrent asset	(17)	(19)
Current liability	(2)	(2)
Noncurrent liability	(25)	(23)
Amortization of net actuarial loss	(1)	(1)
Amortization of prior service cost	0	0
Total Amounts included in comprehensive income	1	(1)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	10	9
Net actuarial loss	10	9
Prior service cost	$ 0	$ 0
Discount rate used to calculate benefit obligation	5.00%	5.47%