Income Taxes (Components Of Net Deferred Income Tax Liability (Asset) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred income tax liabilities [Abstract]
Property, plant and equipment basis differences	$ 2,184	$ 2,182
Intangibles		18
Deferred revenue/expense	65	66
Other, net	56
Gross deferred income tax liability	2,305	2,266
Deferred income tax assets [Abstract]
Pension liability	256	209
Intangibles	665
Tax operating loss carryforward	898	1,027
Employee benefits	184	176
Interest expense deduction limitation carryforward	238	104
Accrued expenses	37	41
Lease obligations	92	33
Tax credit	39	37
Allowance for doubtful accounts	32	26
Other, net	7	1
Gross deferred income tax asset	2,448	1,654
Less: Valuation allowance	(605)	(497)
Net deferred income tax asset	1,843	1,157
Net deferred income tax liability	$ 462	$ 1,109