Retirement and Postretirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Defined benefit pension plans
Postretirement and Other Benefit Plans Disclosure
Employer contributions	$ 2	$ 1	$ 7	$ 4
Pension Benefit
Net periodic benefit costs:
Service cost	2	3	6	9
Interest cost	5	6	15	18
Expected return on plan assets	(7)	(8)	(21)	(25)
Recognized actuarial loss	3	1	7	4
Net periodic benefit cost	3	2	7	6
Postretirement Benefit
Net periodic benefit costs:
Service cost	7	7	21	19
Interest cost	10	10	30	34
Recognized actuarial loss	6	4	20	16
Net periodic benefit cost	$ 23	$ 21	$ 71	$ 69