Retirement and Post-retirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Benefit
Net Periodic Benefit Costs:
Service cost	$ 2	$ 2
Interest cost	4	4
Expected return on plan assets	(6)	(6)
Recognized actuarial loss	2	3
Total	2	3
Post-retirement Benefit
Net Periodic Benefit Costs:
Service cost	5	5
Interest cost	10	10
Recognized actuarial loss	4	5
Total	19	20
Defined benefit plans
Net Periodic Benefit Costs:
Employer contributions	$ 1	$ 1