Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Postretirement benefit accruals	$ 89	$ 102
Pension obligations	465	516
Alternative minimum and other tax credits	291	416
Net operating and capital loss carryforwards	594	665
Compensation reserves	191	174
Other	164	139
Gross deferred income tax assets	1,794	2,012
Less: valuation allowance (a)	(441)	(429)
Net deferred income tax asset	1,353	1,583
Intangibles	(152)	(139)
Investments	(255)	0
Plants, properties and equipment	(1,826)	(2,000)
Forestlands, related installment sales, and investment in subsidiary	(1,453)	(1,454)
Gross deferred income tax liabilities	(3,686)	(3,593)
Net deferred income tax liability	$ (2,333)	$ (2,010)