Note 7 - Credit Losses - Impact of ASC 326 - Allowance for Credit Losses by Portfolio (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)
Beginning Balance	$ 0
Provision for expected credit losses	(186)
Beginning Balance	609
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	795
Trade Accounts Receivable [Member]
Beginning Balance	2,100
Provision for expected credit losses	1,823
Beginning Balance	4,874
Trade Accounts Receivable [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	951
Other Receivables [Member]
Beginning Balance	711
Provision for expected credit losses	1,460
Beginning Balance	4,832
Other Receivables [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	$ 2,661