Note 14 - Stock-based Compensation - Unrecognized Stock-based Compensation Expense (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Remainder of 2019	$ 2,616
2020	2,295
2021	1,534
2022	742
2023	415
2024	32
Total estimated expense	7,634
Stock Appreciation Rights (SARs) [Member]
Remainder of 2019	253
2020	293
2021	235
2022	181
2023	105
2024	7
Total estimated expense	1,074
Restricted Stock [Member]
Remainder of 2019	900
2020	1,053
2021	833
2022	561
2023	310
2024	25
Total estimated expense	3,682
Restricted Stock Units (RSUs) [Member]
Remainder of 2019	248
2020	2
2021
2022
2023
2024
Total estimated expense	250
Performance Shares [Member]
Remainder of 2019	1,215
2020	947
2021	466
2022
2023
2024
Total estimated expense	$ 2,628