Note 13 - Stock-based Compensation (Details Textual) - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Restricted Stock [Member] |
|
|
|
| Allocated Share-based Compensation Expense |
$ 2,343
|
$ 1,696
|
$ 752
|
| Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized |
$ 6,252
|
|
|
| Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition |
2 years 219 days
|
|
|
| Equity Plan 2011 [Member] |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized |
619,153
|
|
|
| Rate of Increase Decrease in Shares Authorized for Issuance |
3.50%
|
|
|
| Equity Plan 2011 [Member] | Restricted Stock [Member] | Minimum [Member] |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |
2 years
|
|
|
| Equity Plan 2011 [Member] | Restricted Stock [Member] | Maximum [Member] |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |
4 years
|
|
|