Pension Plans and Other Post Employment Benefit Plans Components of net periodic benefit cost (credit) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	$ 7	$ 5
Interest Cost	91	141
Expected return on plan assets	(230)	(251)
Amortization of unrecognized loss (gain)	14	1
Settlement/Curtailment Loss (Gain)	1	2
Defined Benefit Plan, Net Periodic Benefit (Credit) Cost	(117)	(102)
Other Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0	1
Interest Cost	6	16
Amortization of unrecognized loss (gain)	23	0
Amortization of Prior Service Benefit	(230)	0
Defined Benefit Plan, Net Periodic Benefit (Credit) Cost	$ (201)	$ 17