Note 18 - Income Taxes - Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets (liabilities):
Net foreign deferred taxes, primarily depreciation	$ (57,202)	$ (61,961)
Depreciation, deferred tax liability	(30,500)	(65,315)
Intangible drilling costs	7,370	13,003
Net operating loss carryforward - U.S.	65,020	55,084
Tax monetization transaction	(17,104)	(13,134)
State and Investment tax credits	813	813
Production tax credits	90,913	85,193
Foreign tax credits	58,072	86,206
Withholding tax	(8,052)	(14,400)
Stock options amortization	1,440	1,166
Basis difference in partnership interest	(36,516)	(16,817)
Accrued liabilities and other	624	3,109
	74,878	72,947
Less - valuation allowance	(22,441)	(77,571)	$ (116,234)	$ (92,898)
Total	$ 52,437
Total		$ (4,624)