Note 3 - Investment Securities (Details Textual) - USD ($) $ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Available-for-sale Securities Pledged as Collateral | $ 191,000 | $ 315,000 |
| Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 656 | 1,833 |
| Available-for-sale Securities | 480,864 | 582,202 |
| Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 7,692 | 3,232 |
| Single Issuer Corporate Debt Security [Member] | ||
| Available-for-sale Securities | 5,500 | |
| Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 793 | |
| Corporate Debt Securities [Member] | ||
| Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 435 | 794 |
| Available-for-sale Securities | 6,125 | 5,840 |
| Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | $ 441 | $ 800 |