Benefit Obligations (Schedule of Net Periodic Benefit Costs Recognized) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 2	$ 6	$ 4
Interest cost	21	29	42	58
Expected return on plan assets	(49)	(47)	(99)	(93)
Special termination benefit	1	0	1	0
Total	(24)	(16)	(50)	(31)
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	0	1	1	1
Expected return on plan assets	0	0	0	0
Special termination benefit	0	0	0	0
Total	$ 0	$ 1	$ 1	$ 1