Note 10 - Income Taxes Summary of Income Tax Examinations (Details) - Internal Revenue Service (IRS) [Member] - USD ($) $ in Millions	Dec. 31, 2016	May 03, 2010	Jun. 30, 2008
Income Tax Examination [Line Items]
Income Tax Examination, Amount of Claimed Income Tax Refund Being Disallowed for Tax Years 2006 and 2007	$ 105
REMIC Residual [Member]
Income Tax Examination [Line Items]
Qualified Deposit With The U.S. Department Of Treasury Relating to Tax Years 2000 Through 2004			$ 85
Qualified Deposit With The U.S. Department Of Treasury Relating To Tax Years 2005 Through 2007		$ 4
Income Tax Examination, Notice of Deficiency, Amounts Related to Unpaid Taxes and Penalties	157
Income Tax Examination, Estimated Interest on Notice of Deficiency Amounts	136
Income Tax Examination, Proposed State Liabilities Resulting from IRS Examination of Tax Years 2000 Through 2007	$ 35