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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Benefits
Net Periodic Benefit Cost [Line Items]
Service cost	$ 5	$ 4	$ 10	$ 8
Interest cost	16	19	32	38
Expected return on plan assets	(18)	(19)	(35)	(37)
Amortization of actuarial losses	7	4	14	6
Amortization of prior service credit	0	0	0	0
Net periodic benefit cost	10	8	21	15
OPEB
Net Periodic Benefit Cost [Line Items]
Service cost	0	0	0	0
Interest cost	4	5	7	8
Expected return on plan assets	0	0	0	0
Amortization of actuarial losses	0	0	2	1
Amortization of prior service credit	(1)	(1)	(2)	(2)
Net periodic benefit cost	$ 3	$ 4	$ 7	$ 7