Note 6 - Income Taxes - Tax Effects of Temporary Differences and Carryforwards of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Loss and tax credit carryforwards	$ 1,465	$ 1,151
Other assets	62	69
Asset impairments and restructuring reserves	154	153
Postretirement medical and life benefits	283	276
Other accrued liabilities	190	265
Other employee benefits	462	505
Gross deferred tax assets	2,616	2,419
Valuation allowance	(270)	(238)
Total deferred tax assets	2,346	2,181
Intangible and other assets	(104)	(181)
Fixed assets	(234)	(284)
Total deferred tax liabilities	(338)	(465)
Net deferred tax assets	$ 2,008	$ 1,716