Retirement Plans and Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension Benefit
Net periodic benefit costs:
Service cost	$ 3	$ 5	$ 9	$ 15
Interest cost	6	7	20	22
Expected return on plan assets	(7)	(9)	(23)	(25)
Amortization of prior service cost	1	1	1	1
Recognized actuarial loss	4	4	14	10
Net periodic benefit cost	7	8	21	23
Employer contributions	1	12	4	16
Postretirement Benefit
Net periodic benefit costs:
Service cost	6	6	19	17
Interest cost	10	11	32	34
Recognized actuarial loss	10	8	27	23
Net periodic benefit cost	$ 26	$ 25	$ 78	$ 74