Note 8 - Credit Losses - Impact of ASC 326 (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Jan. 01, 2020
Allowance for Credit Losses on Receivables	$ 1,673	$ 1,661	$ 2,811
Trade Accounts Receivable [Member]
Allowance for Credit Losses on Receivables	4,546	4,426	2,100
Other Receivables [Member]
Allowance for Credit Losses on Receivables	$ 6,734	$ 4,710	711
Other Assets [Member]
Allowance for Credit Losses on Receivables			0
Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Allowance for Credit Losses on Receivables			7,218
Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Trade Accounts Receivable [Member]
Allowance for Credit Losses on Receivables			3,051
Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Other Receivables [Member]
Allowance for Credit Losses on Receivables			3,372
Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Other Assets [Member]
Allowance for Credit Losses on Receivables			795
Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for Credit Losses on Receivables			4,407
Cumulative Effect, Period of Adoption, Adjustment [Member] | Trade Accounts Receivable [Member]
Allowance for Credit Losses on Receivables			951
Cumulative Effect, Period of Adoption, Adjustment [Member] | Other Receivables [Member]
Allowance for Credit Losses on Receivables			2,661
Cumulative Effect, Period of Adoption, Adjustment [Member] | Other Assets [Member]
Allowance for Credit Losses on Receivables			$ 795