Retirement and Post-retirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined benefit plans
Postretirement and Other Benefit Plans Disclosure
Employer contributions	$ 0	$ 2	$ 2	$ 7
Pension Benefit
Net Periodic Benefit Costs:
Service cost	2	2	6	6
Interest cost	4	5	12	15
Expected return on plan assets	(6)	(7)	(18)	(21)
Recognized actuarial loss	3	3	9	7
Settlement loss			2
Total	3	3	11	7
Post-retirement Benefit
Net Periodic Benefit Costs:
Service cost	4	7	14	21
Interest cost	9	10	29	30
Recognized actuarial loss	3	6	14	20
Total	$ 16	$ 23	$ 57	$ 71