INCOME TAXES - Items Included in Our Deferred Income Tax Assets (Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Postretirement benefits	$ 76	$ 80
Pension	395	260
State tax credits	46	49
Net operating loss carryforwards	25	64
Cellulosic biofuel producers credit	0	78
Other	232	178
Gross deferred tax assets	774	709
Valuation allowance	(56)	(65)
Net deferred tax assets	718	644
Property, plant and equipment	(214)	(169)
Timber installment notes	(180)	(180)
Other	(31)	(41)
Deferred tax liabilities	(425)	(390)
Net deferred tax asset (liability)	$ 293	$ 254