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Note 10 - Derivative Financial Instruments - Statement of Operations Information (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Derivative net gain (loss) | $ 5,324 | $ 6,526 | $ 6,200
Foreign Exchange Forward [Member] | Principal Transactions and Other Income [Member] |  |  |
Derivative net gain (loss) |  | 51 | 87
Other Extended Settlement Trade [Member] | Principal Transactions and Other Income [Member] |  |  |
Derivative net gain (loss) |  | (70) | 60
TBA and Other Forward MBS [Member] | Net Trading [Member] |  |  |
Derivative net gain (loss) | 5,219 | 6,545 | 6,053
Derivatives, Publicity Traded Options [Member] | Other Investments Sold, Not Yet Purchased [Member] |  |  |
Derivative net gain (loss) | $ 105 |  |

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 + Details
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