Retirement Plans (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in plan assets:
Fair value of plan assets at January 1	$ 989
Fair value of plan assets at December 31	998	989
Amounts recognized in the balance sheets consist of:
Noncurrent liabilities	(388)	(284)
Total recognized in accumulated other comprehensive (income) loss	(119)	12	37
Total recognized net periodic benefit cost and other	28	30	46
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at January 1	1,023	962
Service cost	18	17	17
Interest cost	56	56	56
Amendments	9
Actuarial (gain) loss	144	48
Benefits paid	(67)	(60)
Benefit obligation at December 31	1,183	1,023	962
Change in plan assets:
Fair value of plan assets at January 1	989	921
Actual return on plan assets	48	109
Employer contributions	28	19
Benefits paid from plan assets	(67)	(60)
Fair value of plan assets at December 31	998	989	921
Funded status	(185)	(34)
Amounts recognized in the balance sheets consist of:
Noncurrent assets		66
Noncurrent liabilities	(185)	(100)
Net amount recognized	(185)	(34)
Net actuarial (gain) loss	168	7
Recognized actuarial gain (loss)	(7)	(7)
Prior service cost	10
Recognized prior service (cost)	(4)	(5)
Total recognized in accumulated other comprehensive (income) loss	167	(5)
Total recognized net periodic benefit cost and other	180	12
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at January 1	197	206
Service cost	4	4	4
Interest cost	10	12	12
Plan participants' contributions	5	5
Actuarial (gain) loss	15	(11)
Benefits paid	(21)	(20)
Other	2	1
Benefit obligation at December 31	212	197	206
Change in plan assets:
Employer contributions	16	15
Plan participants' contributions	5	5
Benefits paid from plan assets	(21)	(20)
Funded status	(212)	(197)
Amounts recognized in the balance sheets consist of:
Current liabilities	(14)	(13)
Noncurrent liabilities	(198)	(184)
Net amount recognized	(212)	(197)
Net actuarial (gain) loss	15	(11)
Recognized actuarial gain (loss)	1	1
Total recognized in accumulated other comprehensive (income) loss	16	(10)
Total recognized net periodic benefit cost and other	$ 29	$ 5