Divestiture Of Northwest Operations (Narrative) (Details) - USD ($) $ in Millions			3 Months Ended		6 Months Ended
	May 01, 2020	May 28, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Divestiture Of Northwest Operations [Abstract]
Assets held for sale							$ 1,401
Loss on disposal of Northwest Operations			$ 136	$ 384	$ 160	$ 384
Net proceeds	$ 1,131				1,131
Gross proceeds from divestiture		$ 1,352
Escrow withheld					30
Escrow to be disbursed					27
Divestiture revenue			10		10
Fair value of transition services			30		30
Property, plant, and equipment, Derecognized	1,084
Goodwill, Derecognized	658
Valuation allowance, Derecognized	603
Defined benefit pension and other postretirement benefit plan obligations, Derecgonized	142
Out of period adjustment			(27)
Net assets	$ 1,132
Transition services revenue			$ 10		$ 10