Pensions, Other Post-employment Benefits and Employee Benefit Plans Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Benefits
Net Periodic Benefit Cost [Line Items]
Service cost	$ 4	$ 5	$ 8	$ 10
Interest cost	17	16	34	32
Expected return on plan assets	(15)	(18)	(29)	(35)
Amortization of actuarial losses	6	7	11	14
Amortization of prior service credit	0	0	0	0
Net periodic benefit cost	12	10	24	21
OPEB
Net Periodic Benefit Cost [Line Items]
Service cost	0	0	0	0
Interest cost	3	4	6	7
Expected return on plan assets	0	0	0	0
Amortization of actuarial losses	0	0	1	2
Amortization of prior service credit	(1)	(1)	(2)	(2)
Net periodic benefit cost	$ 2	$ 3	$ 5	$ 7