Retirement Plans and Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Benefit
Net periodic benefit costs:
Service cost	$ 3	$ 5	$ 6	$ 10
Interest cost	7	8	14	15
Expected return on plan assets	(8)	(8)	(16)	(16)
Recognized actuarial loss	5	3	10	6
Net periodic benefit cost	7	8	14	15
Employer contributions	2	2	3	4
Postretirement Benefit
Net periodic benefit costs:
Service cost	6	5	13	11
Interest cost	11	12	22	23
Recognized actuarial loss	9	7	17	15
Net periodic benefit cost	$ 26	$ 24	$ 52	$ 49