Note 9 - Income Taxes Income Tax Examinations (Details) - REMIC Residual - Internal Revenue Service (IRS) $ in Millions	Dec. 31, 2018 USD ($)
Income Tax Examination [Line Items]
Qualified Deposit Assets With The U.S. Department Of Treasury Expected to be Submitted	$ 31.0
Refund of Qualified Deposit Assets from U.S. Department of Treasury	$ 57.2

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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