Note 14 - Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring Basis at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Marketable securities - restricted		$ 2,296
Assets, Fair Value Disclosure		2,321
Derivative liabilities	$ 6,689
Fuel Hedge [Member]
Fuel hedge		25
Derivative liabilities	888
Interest Rate Swap [Member]
Derivative liabilities	5,801	3,825
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Marketable securities - restricted		2,296
Assets, Fair Value Disclosure		2,296
Derivative liabilities	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fuel Hedge [Member]
Fuel hedge		0
Derivative liabilities	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Interest Rate Swap [Member]
Derivative liabilities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Marketable securities - restricted		0
Assets, Fair Value Disclosure		0
Derivative liabilities	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fuel Hedge [Member]
Fuel hedge		0
Derivative liabilities	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Interest Rate Swap [Member]
Derivative liabilities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Marketable securities - restricted		0
Assets, Fair Value Disclosure		25
Derivative liabilities	6,689
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fuel Hedge [Member]
Fuel hedge		25
Derivative liabilities	888
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Interest Rate Swap [Member]
Derivative liabilities	$ 5,801	$ 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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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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+ References

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Amount of investment in marketable security.

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