INCOME TAXES - Items Included in Our Deferred Income Tax Assets (Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Postretirement benefits	$ 80	$ 101
Pension	260	369
State tax credits	56	56
Net operating loss carryforwards	59	86
Cellulosic biofuel producers credit	78	100
Other	203	223
Gross deferred tax assets	736	935
Valuation allowance	(72)	(72)
Net deferred tax assets	664	863
Property, plant and equipment	(496)	(523)
Timber installment notes	(180)	(180)
Other	(70)	(130)
Deferred tax liabilities	(746)	(833)
Net deferred tax asset (liability)	$ (82)
Net deferred tax asset (liability)		$ 30