Note 16 - Guarantor Subsidiaries (Details) - Condensed Consolidating Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Income Statements, Captions [Line Items]
Revenues	$ 443,567	$ 500,781	$ 382,589
Cost of sales	(293,567)	(304,446)	(235,316)
Depreciation, depletion, amortization	(111,489)	(111,134)	(81,127)
General and administrative	(34,201)	(31,538)	(28,925)
Gain/(loss) on derivative contracts	8,252	9,134	17,979
Income (loss) before income taxes	(30,658)	12,584	(34,925)
(Provision) benefit from income taxes	(56,310)	5,240	9,795
Net income (loss)	(86,968)	17,824	(25,130)
Comprehensive income (loss)	(87,568)	12,092	(27,511)
Preferred stock dividends	(552)	(552)	(552)
Income (loss) applicable to common stockholders	(87,520)	17,272	(25,682)
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Equity in earnings (loss) of subsidiaries	(49,565)	(72,407)	15,807
Other (expense) income	54,188	(16,295)	(16,922)
Income (loss) before income taxes	4,623	(88,702)	(1,115)
(Provision) benefit from income taxes	(54,188)	16,295	16,922
Net income (loss)	(49,565)	(72,407)	15,807
Changes in comprehensive income (loss)	208	177	4,594
Comprehensive income (loss)	(49,357)	(72,230)	20,401
Income (loss) applicable to common stockholders	(49,565)	(72,407)	15,807
Consolidated [Member]
Condensed Income Statements, Captions [Line Items]
Revenues	443,567	500,781	382,589
Cost of sales	(293,567)	(304,446)	(235,316)
Depreciation, depletion, amortization	(111,489)	(111,134)	(81,127)
General and administrative	(34,201)	(31,538)	(28,925)
Exploration and pre-development	(21,958)	(19,667)	(37,650)
Gain/(loss) on derivative contracts	8,252	9,134	17,979
Closed operations	(2,162)		(26,397)
Other (expense) income	(19,100)	(30,546)	(26,078)
Income (loss) before income taxes	(30,658)	12,584	(34,925)
(Provision) benefit from income taxes	(56,310)	5,240	9,795
Net income (loss)	(86,968)	17,824	(25,130)
Changes in comprehensive income (loss)	(600)	(5,732)	(2,381)
Comprehensive income (loss)	(87,568)	12,092	(27,511)
Preferred stock dividends	(552)	(552)	(552)
Income (loss) applicable to common stockholders	(87,520)	17,272	(25,682)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Revenues	6,194	1,473	3,044
General and administrative	(17,920)	(17,667)	(14,441)
Exploration and pre-development	(627)	(252)	(576)
Gain/(loss) on derivative contracts	8,252	9,134	17,979
Closed operations	(517)		(14,444)
Equity in earnings (loss) of subsidiaries	49,565	72,407	(15,807)
Other (expense) income	(131,915)	(47,271)	(885)
Income (loss) before income taxes	(86,968)	17,824	(25,130)
Net income (loss)	(86,968)	17,824	(25,130)
Changes in comprehensive income (loss)	(600)	(5,732)	(2,381)
Comprehensive income (loss)	(87,568)	12,092	(27,511)
Preferred stock dividends	(552)	(552)	(552)
Income (loss) applicable to common stockholders	(87,520)	17,272	(25,682)
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Revenues	287,941	333,460	304,423
Cost of sales	(192,683)	(194,600)	(179,491)
Depreciation, depletion, amortization	(67,815)	(72,937)	(63,097)
General and administrative	(14,508)	(12,694)	(13,174)
Exploration and pre-development	(7,177)	(7,088)	(24,990)
Closed operations	(1,645)
Other (expense) income	22,537	29,753	1,345
Income (loss) before income taxes	26,650	75,894	25,016
(Provision) benefit from income taxes	(7,251)	(10,565)	(14,171)
Net income (loss)	19,399	65,329	10,845
Changes in comprehensive income (loss)	(467)	(1,329)	(7)
Comprehensive income (loss)	18,932	64,000	10,838
Income (loss) applicable to common stockholders	19,399	65,329	10,845
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Revenues	149,432	165,848	75,122
Cost of sales	(100,884)	(109,846)	(55,825)
Depreciation, depletion, amortization	(43,674)	(38,197)	(18,030)
General and administrative	(1,773)	(1,177)	(1,310)
Exploration and pre-development	(14,154)	(12,327)	(12,084)
Closed operations			(11,953)
Other (expense) income	36,090	3,267	(9,616)
Income (loss) before income taxes	25,037	7,568	(33,696)
(Provision) benefit from income taxes	5,129	(490)	7,044
Net income (loss)	30,166	7,078	(26,652)
Changes in comprehensive income (loss)	259	1,152	(4,587)
Comprehensive income (loss)	30,425	8,230	(31,239)
Income (loss) applicable to common stockholders	$ 30,166	$ 7,078	$ (26,652)