Retirement and Postretirement Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Benefit
Net periodic benefit costs:
Service cost	$ 3	$ 3	$ 6	$ 7
Interest cost	6	7	12	13
Expected return on plan assets	(9)	(8)	(17)	(16)
Recognized actuarial loss	2	4	3	8
Net periodic benefit cost	2	6	4	12
Employer contributions	2	1	3	2
Postretirement Benefit
Net periodic benefit costs:
Service cost	6	7	12	14
Interest cost	12	10	24	21
Recognized actuarial loss	6	10	12	20
Net periodic benefit cost	$ 24	$ 27	$ 48	$ 55