Leases (Components Of Lease Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Depreciation of finance lease ROU assets	$ 35
Interest on finance lease liabilities	5
Operating lease cost	26
Variable lease cost	3
Sublease income	(2)	$ (1)
Total lease cost	$ 67