Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 65	$ 53	$ 130	$ 107
Interest cost	18	31	35	60
Expected return on plan assets	(87)	(86)	(173)	(165)
Amortization:
Net loss	64	50	129	95
Prior service cost	1	0	1	0
Net periodic pension cost	$ 61	$ 48	$ 122	$ 97