Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Restricted Cash and Cash Equivalents, Noncurrent, Total	$ 1,025	$ 1,025
Capitalized Drilling Costs	14,400	11,600	$ 9,900
Foreign Currency Transaction Gain (Loss), Realized	(8,236)	10,310	$ (9,680)
Operating Lease, Liability, Total	16,398
Operating Lease, Right-of-Use Asset	$ 16,381	$ 0
Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability, Total				$ 22,400
Operating Lease, Right-of-Use Asset				$ 22,400
Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	17 years