Pension Plans, Retirement Benefits and Savings Plans (details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 32	$ 28	$ 65	$ 55
Interest cost on benefit obligation	36	37	72	75
Expected return on plan assets	(57)	(55)	(115)	(109)
Net periodic benefit cost, amortization of unrecognized net actuarial (gain) loss	24	16	48	32
Net periodic benefit cost	35	26	70	53
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Interest cost on benefit obligation	2	3	5	5
Net periodic benefit cost, amortization of unrecognized prior service benefit			(1)	(1)
Net periodic benefit cost, amortization of unrecognized net actuarial (gain) loss		(1)		(1)
Net periodic benefit cost	$ 2	$ 2	$ 4	$ 3