INCOME TAXES - Items Included in Our Deferred Income Tax Assets (Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Components Of Deferred Tax Assets And Liabilities [Abstract]
Pension and postretirement benefits	$ 159	$ 112
State tax credits	53	51
Depletion	34	41
Excess interest	55	30
Incentive compensation	17	20
Workers compensation	18	18
Net operating loss carryforwards	28	19
Other	101	96
Gross deferred tax assets	465	387
Valuation allowance	(64)	(61)
Net deferred tax assets	401	326
Property, plant and equipment	(224)	(197)
Timber installment notes	(74)	(116)
Other	(37)	(41)
Net deferred tax liabilities	(335)	(354)
Net deferred tax asset (liability)	$ 66	$ (28)