Note 18 - Income Taxes - Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets (liabilities):
Net foreign deferred taxes, primarily depreciation	$ (88,508)	$ (57,202)
Depreciation, deferred tax liability	(21,958)	(30,500)
Intangible drilling costs, liability	(1,405)
Intangible drilling costs, asset		7,370
Net operating loss carryforward - U.S.	45,307	65,020
Tax monetization transaction	(30,964)	(17,104)
Right-of-use assets	(3,715)	0
Lease liabilities	3,755	0
State and Investment tax credits	813	813
Production tax credits	100,524	90,913
Foreign tax credits	92,497	58,072
Withholding tax	(15,539)	(8,052)
Stock options amortization	1,409	1,440
Basis difference in partnership interest	(39,622)	(36,516)
Excess business interest	6,189	0
Accrued liabilities and other	1,013	624
	49,796	74,878
Less - valuation allowance	(17,412)	(22,441)	$ (77,571)	$ (116,234)
Total	$ 32,384	$ 52,437