Pensions, Other Post-employment Benefits and Employee Benefit Plans Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Benefits
Net Periodic Benefit Cost [Line Items]
Service cost	$ 5	$ 5	$ 13	$ 15
Interest cost	17	18	51	50
Expected return on plan assets	(14)	(18)	(43)	(53)
Amortization of actuarial losses	6	6	17	20
Amortization of prior service credit	0	0	0	0
Net periodic benefit cost	14	11	38	32
OPEB
Net Periodic Benefit Cost [Line Items]
Service cost	0	0	0	0
Interest cost	3	3	9	10
Expected return on plan assets	0	0	0	0
Amortization of actuarial losses	1	2	2	4
Amortization of prior service credit	(1)	(1)	(3)	(3)
Net periodic benefit cost	$ 3	$ 4	$ 8	$ 11