Note 18 - Income Taxes - Significant Components of Deferred Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other deferred tax expense (exclusive of the effect of other components listed below)	$ 4,337	$ (1,822)	$ 2,034
Usage (benefit) of operating loss carryforwards - U.S.	72,293	(28,065)	(5,576)
Change in valuation allowance	(38,548)	23,336	(40,999)
Change in foreign valuation allowance			(49,701)
Change in foreign income tax	25,502	23,724	14,365
Change in lease transaction			4,574
Change in tax monetization transaction	(3,091)	51,040	16,004
Change in depreciation	(29,265)	(42,411)	(205)
Change in foreign tax credits	(86,206)
Change in withholding tax	14,400
Change in state and investment tax credits	(144)
Change in intangible drilling costs	19,008	4,511	4,932
Change in production tax credits and alternative minimum tax credit	(2,086)	(11,643)	610
Basis difference in partnership interests	(9,700)	5,111	18,794
	$ (33,500)	$ 23,781	$ (35,168)