Postretirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure
Net loss	$ (51)	$ 78	$ 83
Total recognized in comprehensive income	2	(2)	0
Other Benefits
Defined Benefit Plan Disclosure
Net loss	0	1	(2)
Defined Benefit Plan, Prior Service Credit	0	(5)	0
Amortization of prior service credit	3	3	4
Amortization of net actuarial loss	(2)	(2)	(2)
Change recognized in other comprehensive loss	$ 1	$ (3)	$ 0