Note 15 - Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring Basis at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivate liabilities	$ 4,190
Marketable securities - restricted (Note 4)		$ 2,296
Assets, Fair Value Disclosure		2,321
Fuel Hedge [Member]
Derivate liabilities	297
Fuel hedge		25
Interest Rate Swap [Member]
Derivate liabilities	3,893	3,825
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Derivate liabilities	0
Marketable securities - restricted (Note 4)		2,296
Assets, Fair Value Disclosure		2,296
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
Marketable securities - restricted (Note 4)		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
Marketable securities - restricted (Note 4)		0
Assets, Fair Value Disclosure		25
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fuel Hedge [Member]
Derivate liabilities	297
Fuel hedge		25
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Interest Rate Swap [Member]
Derivate liabilities	$ 3,893	$ 3,825

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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