Consolidated Statements of Operations and Comprehensive (Loss) Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Total revenues	$ 14,653	$ 20,140	$ 50,909	$ 55,264
Costs and expenses:
Production	3,162	2,307	8,376	7,980
Exploration, abandonment and impairment	488	162	6,267	393
Seismic and other exploration	48	122	233	340
General and administrative	2,503	2,539	8,247	9,662
Depreciation, depletion and amortization	3,021	2,938	10,179	10,673
Accretion of asset retirement obligations	56	35	157	124
Total costs and expenses	10,540	9,157	37,261	32,557
Operating income	4,113	10,983	13,648	22,707
Other income (expense):
Interest and other expense	(2,780)	(2,776)	(8,011)	(7,649)
Interest and other income	381	211	776	842
Gain (loss) on derivative contracts	403	(1,290)	(30)	(5,156)
Foreign exchange loss	(797)	(2,991)	(2,185)	(6,987)
Total other expense	(2,793)	(6,846)	(9,450)	(18,950)
Income from operations before income taxes	1,320	4,137	4,198	3,757
Income tax expense	(250)	(5,857)	(7,039)	(8,258)
Net income (loss)	1,070	(1,720)	(2,841)	(4,501)
Other comprehensive income (loss):
Foreign currency translation adjustment	808	(11,765)	(3,834)	(23,217)
Comprehensive income (loss)	$ 1,878	$ (13,485)	$ (6,675)	$ (27,718)
Net income (loss) per common share
Basic net income (loss) per common share	$ 0.02	$ (0.03)	$ (0.05)	$ (0.09)
Weighted average common shares outstanding	57,680	50,597	54,249	50,465
Diluted net income (loss) per common share	$ 0.02	$ (0.03)	$ (0.05)	$ (0.09)
Weighted average common and common equivalent shares outstanding	57,680	50,597	54,249	50,465
Oil and Natural Gas Sales [Member]
Revenues:
Total revenues	$ 14,543	$ 20,098	$ 50,537	$ 54,859
Other [Member]
Revenues:
Total revenues	110	42	372	405
Transportation and Processing [Member]
Costs and expenses:
Cost of goods and services sold	$ 1,262	$ 1,054	$ 3,802	$ 3,385