Income Taxes (Components Of Net Deferred Income Tax Liability (Asset) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax liabilities [Abstract]
Property, plant and equipment basis differences	$ 2,022	$ 2,751
Intangibles	140	878
Deferred Revenue/Expense	8	14
Other, net	4	12
Gross deferred income tax liability	2,174	3,655
Deferred income tax assets [Abstract]
Pension liability	176	273
Tax operating loss carryforward	960	687
Employee benefits	192	255
Accrued expenses	23	44
Capital Lease Obligations	39	75
Tax Credits	43	30
Allowance for doubtful accounts	7	44
Other, net	2	2
Gross deferred income tax asset	1,442	1,410
Less: Valuation allowance	(407)	(271)
Net deferred income tax asset	1,035	1,139
Net deferred income tax liability	$ 1,139	$ 2,516