Pension Plans and Other Post Employment Benefit Plans Components of net periodic benefit cost (credit) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	$ 7	$ 6	$ 19	$ 19
Interest Cost	91	139	273	420
Expected return on plan assets	(228)	(250)	(686)	(750)
Amortization of unrecognized loss (gain)	14	1	41	3
Amortization of Prior Service Benefit	0	0	(1)	(1)
Settlement/Curtailment Loss (Gain)	0	0	1	3
Defined Benefit Plan, Net Periodic Benefit (Credit) Cost	(116)	(104)	(353)	(306)
Other Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	1	0	1	1
Interest Cost	5	16	16	49
Amortization of unrecognized loss (gain)	23	1	70	1
Amortization of Prior Service Benefit	(231)	0	(692)	0
Defined Benefit Plan, Net Periodic Benefit (Credit) Cost	(202)	17	(606)	51
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	$ 0	$ 0	$ (1)	$ 0