Note 13 - Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring Basis at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Derivate liabilities		$ 4,190
Assets, Fair Value Disclosure	$ 3,103
Fuel Hedge [Member]
Derivate liabilities		297
Fuel hedge	58
Interest Rate Swap [Member]
Derivate liabilities	3,045	3,893
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Derivate liabilities		0
Assets, Fair Value Disclosure	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Fuel Hedge [Member]
Derivate liabilities		0
Fuel hedge	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Swap [Member]
Derivate liabilities	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Derivate liabilities		0
Assets, Fair Value Disclosure	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Fuel Hedge [Member]
Derivate liabilities		0
Fuel hedge	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Derivate liabilities	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Derivate liabilities		4,190
Assets, Fair Value Disclosure	3,103
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Fuel Hedge [Member]
Derivate liabilities		297
Fuel hedge	58
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member]
Derivate liabilities	$ 3,045	$ 3,893