Note 1 - Basis of Presentation (Tables)

6 Months Ended

Jun. 30, 2018

Notes Tables

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

Three Months Ended				Six Months Ended
June 30,				June 30,
2018		2017		2018		2017
$	574	$	635	$	914	$	1,069

Three Months Ended				Six Months Ended
June 30,				June 30,
2018		2017		2018		2017
$	221	$	344	$	468	$	680

Three Months Ended				Six Months Ended
June 30,				June 30,
2018		2017		2018		2017
$	84	$	-	$	84	$	-

Share-based Compensation, Stock Options, Activity [Table Text Block]

	Number of Shares			Weighted Average Option Exercise Price Per Share		Weighted Average Grant Date Fair Value Per Share
Outstanding, December 31, 2017		8,317		$	2.35	$	1.67
Granted		300		$	2.80	$	1.87
Exercised		(365	)	$	1.70	$	1.18
Forfeited		(335	)	$	2.17	$	1.55
Outstanding, June 30, 2018		7,917		$	2.40	$	1.71

Nonvested Restricted Stock Shares Activity [Table Text Block]

	Number of Shares			Weighted Average Grant Date Fair Value Per Share
Unvested, December 31, 2017		1,479		$	3.43
Granted		753		$	2.22
Vested/ Released		(733	)	$	3.15
Forfeited		(77	)	$	3.16
Unvested June 30, 2018		1,422		$	2.95

Schedule of Nonvested Performance-based Units Activity [Table Text Block]

	Number of Shares			Weighted Average Option Exercise Price Per Share
Unvested, December 31, 2017		-		$	-
Granted		464		$	2.37
Vested/ Released		-		$	-
Forfeited		(31	)	$	2.37
Unvested June 30, 2018		433		$	2.37

Schedule of Change in Asset Retirement Obligation [Table Text Block]

	June 30, 2018			December 31, 2017
Beginning future site restoration obligation	$	8,775		$	8,623
New wells placed on production and other		452			1,088
Deletions related to property disposals and plugging costs		(445	)		(1,551	)
Accretion expense and other		264			451
Revisions and other		29			164
Ending future site restoration obligation	$	9,075		$	8,775