Note 14 - Fair Value - Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Net derivative asset (liability)	$ (15,402)	$ (4,023)
Fair Value, Inputs, Level 1 [Member]
Net derivative asset (liability)
Fair Value, Inputs, Level 2 [Member]
Net derivative asset (liability)	(15,402)	(4,023)
Fair Value, Inputs, Level 3 [Member]
Net derivative asset (liability)
Commodity Contract [Member] | Fair Value, Recurring [Member]
Net derivative asset (liability)	(839)	265
Commodity Contract [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Net derivative asset (liability)
Commodity Contract [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Net derivative asset (liability)	(839)	265
Commodity Contract [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Net derivative asset (liability)
Interest Rate Swap [Member] | Fair Value, Recurring [Member]
Net derivative asset (liability)	(14,563)	(4,288)
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Net derivative asset (liability)
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Net derivative asset (liability)	(14,563)	(4,288)
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Net derivative asset (liability)