Benefit Plans, Projected and Accumulated Benefit Obligation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Changes in plan assets: [Roll Forward]
Fair value of plan assets at end of year	$ 343	$ 294
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Accrued liabilities	12	16
Pension Benefits [Member]
Change in projected benefit obligation: [Roll Forward]
Projected benefit obligations at beginning of year	564	511
Service cost	27	39	36
Interest cost	30	27	27
Actuarial loss	47	45
Benefits paid	(38)	(62)
Plan amendments	0	0
Curtailments	0	4
Projected benefit obligations at end of year	630	564	511
Changes in plan assets: [Roll Forward]
Fair value of plan assets at beginning of year	294	262
Actual return on plan assets	28	30
Employer contributions	59	64
Benefits paid	(38)	(62)
Fair value of plan assets at end of year	343	294	262
Funded status of plan [Abstract]
Funded status at end of year	(287)	(270)
Accumulated benefit obligation	480	431
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Accrued liabilities	2	8
Other noncurrent liabilities	285	262
Total amount recognized	287	270
Other Postretirement Benefits [Member]
Change in projected benefit obligation: [Roll Forward]
Projected benefit obligations at beginning of year	96	356
Service cost	5	11	16
Interest cost	4	14	20
Actuarial loss	5	85
Benefits paid	(7)	(6)
Plan amendments	(3)	(317)
Curtailments	0	(47)
Projected benefit obligations at end of year	100	96	356
Changes in plan assets: [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	7	6
Benefits paid	(7)	(6)
Fair value of plan assets at end of year	0	0	0
Funded status of plan [Abstract]
Funded status at end of year	(100)	(96)
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Accrued liabilities	10	8
Other noncurrent liabilities	90	88
Total amount recognized	$ 100	$ 96