Employment Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 9	$ 11	$ 19	$ 23
Interest Cost	24	23	48	45
Expected return on plan assets	(33)	(31)	(67)	(62)
Amortization of net loss	0	4	0	8
Net cost recognized	0	7	0	14
Retiree Health and Welfare Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	0	1
Interest Cost	3	3	6	6
Amortization of Prior Service Credits			(1)	0
Amortization of net loss	0	1	1	2
Net cost recognized	$ 3	$ 5	$ 6	$ 9