Note 13 - Stock-based Compensation and Similar Arrangements - Nonvested Stock Activity (Details) - Restricted Stock [Member] |
12 Months Ended |
|---|---|
|
Dec. 31, 2016
$ / shares
shares
| |
| Non-vested at beginning of period (in shares) | shares | 44,182 |
| Non-vested at beginning of period (in dollars per share) | $ / shares | $ 38.67 |
| Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares | 57,964 |
| Granted (in dollars per share) | $ / shares | $ 44.90 |
| Vested (in shares) | shares | (26,100) |
| Vested (in dollars per share) | $ / shares | $ 35.53 |
| Forfeited or cancelled (in shares) | shares | (3,848) |
| Forfeited or cancelled (in dollars per share) | $ / shares | $ 44.63 |
| Non-vested at end of period (in shares) | shares | 72,198 |
| Non-vested at end of period (in dollars per share) | $ / shares | $ 44.44 |