Retirement Benefits (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Net Periodic Benefit Cost (Table Amounts) [Abstract]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit	$ (655)	$ 536	$ (950)
Pension Benefits
Components of Net Periodic Benefit Cost (Table Amounts) [Abstract]
Service cost	404	388	390
Interest cost	1,226	1,250	1,302
Expected return on plan assets	(2,217)	(1,885)	(1,853)
Amortization of prior service credit	(58)	(57)	(60)
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit	(699)	445	(1,041)
Other	0	(7)	0
Net periodic benefit cost	54	(756)	820
Medical and Life Benefits
Components of Net Periodic Benefit Cost (Table Amounts) [Abstract]
Service cost	21	20	29
Interest cost	76	85	95
Expected return on plan assets	(101)	(89)	(86)
Amortization of prior service credit	(21)	(22)	(22)
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit	44	91	91
Other	0	0	0
Net periodic benefit cost	$ (69)	$ (97)	$ (75)