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, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits
Net Periodic Benefit Cost [Line Items]
Service cost	$ 5	$ 4	$ 15	$ 12
Interest cost	18	19	50	57
Expected return on plan assets	(18)	(19)	(53)	(56)
Amortization of actuarial losses	6	2	20	8
Amortization of prior service credit	0	0	0	0
Net periodic benefit cost	11	6	32	21
OPEB
Net Periodic Benefit Cost [Line Items]
Service cost	0	0	0	0
Interest cost	3	4	10	12
Expected return on plan assets	0	0	0	0
Amortization of actuarial losses	2	1	4	2
Amortization of prior service credit	(1)	(2)	(3)	(4)
Net periodic benefit cost	$ 4	$ 3	$ 11	$ 10