Pension Plans, Retirement Benefits and Savings Plans (details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 33	$ 27	$ 98	$ 82
Interest cost on benefit obligation	36	38	108	113
Expected return on plan assets	(58)	(55)	(173)	(164)
Net periodic benefit cost, amortization of unrecognized net actuarial (gain) loss	24	17	72	49
Net periodic benefit cost	35	27	105	80
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Interest cost on benefit obligation	3	3	8	8
Net periodic benefit cost, amortization of unrecognized prior service benefit	(1)	(1)	(2)	(2)
Net periodic benefit cost, amortization of unrecognized net actuarial (gain) loss		(1)		(2)
Net periodic benefit cost	$ 2	$ 1	$ 6	$ 4