Pension and Other Postemployment Benefits (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 224	$ 208	$ 191
Interest cost	372	390	398
Expected return on plan assets	(574)	(448)	(399)
Amortization of prior service cost (credit)	7	7	8
Special termination costs	31	0	0
Pension & OPEB mark-to-market adjustment	227	108	179
Net periodic benefit cost (credit)	287	265	377
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	5	5	5
Interest cost	25	27	30
Expected return on plan assets	(31)	(30)	(30)
Amortization of prior service cost (credit)	(81)	(81)	(80)
Special termination costs	8	0	0
Pension & OPEB mark-to-market adjustment	(82)	13	15
Net periodic benefit cost (credit)	$ (156)	$ (66)	$ (60)