Retirement Benefits (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Components of Net Periodic Benefit Cost (Table Amounts) [Abstract]
Service cost	$ 446	$ 484	$ 457
Interest cost	1,284	1,224	1,260
Expected return on plan assets	(1,853)	(1,975)	(1,871)
Amortization of:
Prior service credit	(60)	(60)	(59)
Net loss from previous years	714	682	327
Other	0	0	1
Net periodic benefit cost	531	355	115
Medical and Life Benefits
Components of Net Periodic Benefit Cost (Table Amounts) [Abstract]
Service cost	30	35	34
Interest cost	94	94	99
Expected return on plan assets	(86)	(89)	(83)
Amortization of:
Prior service credit	(22)	(28)	(45)
Net loss from previous years	16	27	13
Other	0	0	0
Net periodic benefit cost	$ 32	$ 39	$ 18