Pensions, Other Post-employment Benefits and Employee Benefit Plans Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits
Net Periodic Benefit Cost [Line Items]
Service cost	$ 4	$ 5
Interest cost	17	16
Expected return on plan assets	(14)	(17)
Amortization of actuarial losses	5	7
Amortization of prior service credit	0	0
Net periodic benefit cost	12	11
OPEB
Net Periodic Benefit Cost [Line Items]
Service cost	0	0
Interest cost	3	3
Expected return on plan assets	0	0
Amortization of actuarial losses	1	2
Amortization of prior service credit	(1)	(1)
Net periodic benefit cost	$ 3	$ 4