Retirement Plans and Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Plans
Net periodic benefit costs:
Service cost	$ 3	$ 5
Interest cost	7	7
Expected return on plan assets	(8)	(8)
Recognized actuarial loss	5	3
Net periodic benefit cost	7	7
Employer contributions	1	2
Postretirement Plans
Net periodic benefit costs:
Service cost	7	6
Interest cost	11	11
Recognized actuarial loss	8	8
Net periodic benefit cost	$ 26	$ 25