Note 6 - Income Taxes (Details) - Tax Effects of Temporary Differences and Carryforwards of Deferred Tax Assets and Liabilities - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Tax Effects of Temporary Differences and Carryforwards of Deferred Tax Assets and Liabilities [Abstract]
Loss and tax credit carryforwards	$ 1,151	$ 1,235
Other assets	69	69
Asset impairments and restructuring reserves	153	170
Postretirement medical and life benefits	276	312
Other accrued liabilities	265	246
Other employee benefits	505	473
Gross deferred tax assets	2,419	2,505
Valuation allowance	(238)	(298)
Total deferred tax assets	2,181	2,207
Intangible and other assets	(181)	(152)
Fixed assets	(284)	(299)
Total deferred tax liabilities	(465)	(451)
Net deferred tax assets	$ 1,716	$ 1,756