Postretirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure
Net loss	$ 83	$ 37	$ 19
Total recognized in comprehensive income	0	0	(6)
Other Benefits
Defined Benefit Plan Disclosure
Net loss	(2)	1	(5)
Defined Benefit Plan, Prior Service Credit	0	(3)	(3)
Amortization of prior service credit	4	4	3
Amortization of net actuarial loss	(2)	(2)	(2)
Foreign Exchange/Other	0	0	(1)
Change recognized in other comprehensive loss	$ 0	$ 0	$ (8)