Note 3 - Revenues From Contracts With Customers; Other Revenues (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 5,058	$ 9,420	$ 11,461	$ 17,663
Contract with Customer, Asset, after Allowance for Credit Loss, Total	0		0		$ 0
Contract with Customer, Asset, Credit Loss Expense (Reversal)	0	0	0	0
Contract with Customer, Liability, Total	0		0		0
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	5,058	9,420	11,461	17,638
Transferred at Point in Time [Member] | Variable Consideration or Multiple Performance Obligations [Member]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Revenue, Remaining Performance Obligation, Amount	0		0		$ 0
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax				25
Transferred over Time [Member] | Variable Consideration or Multiple Performance Obligations [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 0	$ 0	$ 0	$ 0