Divestiture Of Northwest Operations (Narrative) (Details) - USD ($) $ in Millions			2 Months Ended	3 Months Ended	12 Months Ended
	May 01, 2020	May 28, 2019	Feb. 28, 2021	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Gross proceeds from divestiture		$ 1,352
Net proceeds	$ 1,131				$ 1,131
Escrow to be disbursed					58
Fair value of transition services					30
Net assets	1,132
Property, plant, and equipment, Derecognized	1,084
Goodwill, Derecognized	658
Valuation allowance, Derecognized	603
Defined benefit pension and other postretirement benefit plan obligations, Derecognized	$ 150
Loss on disposal of Northwest Operations					162	$ 446
Out of period adjustment				$ 27
Subsequent Event [Member]
Defined Benefit Plan Disclosure [Line Items]
Escrow to be disbursed			$ 25
Working capital			$ 5
Northwest Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Transition services revenue					$ 30