Retirement 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 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 14	$ 10	$ 27	$ 20
Interest cost on projected benefit obligation	22	20	44	40
Expected return on plan assets	(32)	(23)	(64)	(47)
Amortization of unrecognized loss	6	4	13	9
Net periodic benefit cost	10	11	20	22
Postretirement Benefits Other Than Pensions (OPEB) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	4	2	9	5
Interest cost on projected benefit obligation	8	5	15	10
Expected return on plan assets		1
Amortization of prior service cost/(credit)	(1)	(1)	(2)	(2)
Amortization of unrecognized loss	2		5	1
Net periodic benefit cost	$ 13	$ 7	$ 27	$ 14