Divestiture Of Northwest Operations (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended
	May 01, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Escrow held		$ 27
Escrow received		25
Working capital		$ 5
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			$ 24
Northwest Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Gross proceeds from divestiture	1,352
Net proceeds	$ 1,131