Note 3 - Investment Securities - Amorized Cost and Fair Value of Held-to-maturity Debt Securities (Details) - USD ($) |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Held-to-maturity Securities | $ 26,329,000 | $ 27,458,000 |
| Held-to-Maturity Securities, Gross Unrealized Gains | 27,000 | 439,000 |
| Held-to-Maturity Securities, Gross Unrealized Losses | 462,000 | 54,000 |
| Investment securities held-to-maturity | 25,894,000 | 27,843,000 |
| Collateralized Mortgage Backed Securities [Member] | ||
| Held-to-maturity Securities | 5,021,000 | 6,097,000 |
| Held-to-Maturity Securities, Gross Unrealized Gains | 2,000 | |
| Held-to-Maturity Securities, Gross Unrealized Losses | 29,000 | 16,000 |
| Investment securities held-to-maturity | 4,994,000 | 6,081,000 |
| US States and Political Subdivisions Debt Securities [Member] | ||
| Held-to-maturity Securities | 21,308,000 | 21,361,000 |
| Held-to-Maturity Securities, Gross Unrealized Gains | 25,000 | 439,000 |
| Held-to-Maturity Securities, Gross Unrealized Losses | 433,000 | 38,000 |
| Investment securities held-to-maturity | $ 20,900,000 | $ 21,762,000 |