Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 68	$ 54	$ 198	$ 161
Interest cost	19	29	54	89
Expected return on plan assets	(92)	(82)	(265)	(247)
Amortization:
Net loss	68	47	197	142
Prior service cost	0	0	1	0
Net periodic pension cost	$ 63	$ 48	$ 185	$ 145