Note 16 - Benefit Plans - Fair Value of Pension Plan's Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair values of the Pension Plan's assets	$ 0	$ 61,870	$ 58,014
Fair Value, Inputs, Level 1 [Member]
Fair values of the Pension Plan's assets		51,736
Fair Value, Inputs, Level 3 [Member]
Fair values of the Pension Plan's assets		10,134
Mutual Fund [Member]
Fair values of the Pension Plan's assets		51,736
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Fair values of the Pension Plan's assets		51,736
Mutual Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Fair values of the Pension Plan's assets		0
Other Investment [Member]
Fair values of the Pension Plan's assets		10,134
Other Investment [Member] | Fair Value, Inputs, Level 1 [Member]
Fair values of the Pension Plan's assets		0
Other Investment [Member] | Fair Value, Inputs, Level 3 [Member]
Fair values of the Pension Plan's assets		$ 10,134	$ 9,700