Note 13 - Oil and Natural Gas Producing Activities (Unaudited) - Net Proved Oil and Natural Gas Reserves (Details)		12 Months Ended
		Dec. 31, 2019 MMBbls MMcf	Dec. 31, 2018 MMBbls MMcf	Dec. 31, 2017 MMBbls MMcf
Natural Gas and Natural Gas Liquids [Member]
Net proved reserves at beginning of period (Millions Cubic Feet)		470,937	415,224	286,038
Revisions of previous estimates (1) (Millions Cubic Feet)	[1]	37,136	(16,993)	106,639
Extensions, discoveries and improved recovery (2) (Millions Cubic Feet)	[2]	218,015	100,499	32,871
Purchases of minerals in place (Millions Cubic Feet)
Sales of minerals in place (Millions Cubic Feet)		(169,310)	(3,349)
Production (Millions Cubic Feet)		(46,712)	(24,444)	(10,324)
Net proved reserves at end of period (Millions Cubic Feet)		510,066	470,937	415,224
Beginning of period (Millions Cubic Feet)		92,118	52,861	21,872
End of period (Millions Cubic Feet)		138,607	92,118	52,861
Beginning of period (Millions Cubic Feet)		378,819	362,363	264,166
End of period (Millions Cubic Feet)		371,459	378,819	362,363
Crude Oil and Natural Gas Liquids (NGL) [Member]
Net proved reserves at beginning of period (Millions Cubic Feet) | MMBbls		1,441	2,130	2,815
Revisions of previous estimates (1) (Millions Cubic Feet) | MMBbls	[1]	(166)	(388)	(381)
Extensions, discoveries and improved recovery (2) (Millions Cubic Feet) | MMBbls	[2]
Purchases of minerals in place (Millions Cubic Feet) | MMBbls
Sales of minerals in place (Millions Cubic Feet) | MMBbls			(84)
Production (Millions Cubic Feet) | MMBbls		(171)	(217)	(304)
Net proved reserves at end of period (Millions Cubic Feet) | MMBbls		1,104	1,441	2,130
Beginning of period (Millions Cubic Feet) | MMBbls		1,441	2,130	2,815
End of period (Millions Cubic Feet) | MMBbls		1,104	1,441	2,130
Beginning of period (Millions Cubic Feet) | MMBbls
End of period (Millions Cubic Feet) | MMBbls
Natural Gas Equivalents [Member]
Net proved reserves at beginning of period (Millions Cubic Feet)		479,583	428,002	302,927
Revisions of previous estimates (1) (Millions Cubic Feet)	[1]	36,141	(19,320)	104,354
Extensions, discoveries and improved recovery (2) (Millions Cubic Feet)	[2]	218,015	100,499	32,871
Purchases of minerals in place (Millions Cubic Feet)
Sales of minerals in place (Millions Cubic Feet)	[3]	(169,310)	(3,852)
Production (Millions Cubic Feet)		(47,738)	(25,746)	(12,150)
Net proved reserves at end of period (Millions Cubic Feet)		516,691	479,583	428,002
Beginning of period (Millions Cubic Feet)		100,764	65,639	44,432
End of period (Millions Cubic Feet)		145,232	100,764	65,639
Beginning of period (Millions Cubic Feet)		378,819	362,363	258,495
End of period (Millions Cubic Feet)		371,459	378,819	362,363

[1] Revisions of previous estimates in 2019 were positive, primarily due to improved well performance. Revisions of previous estimates in 2018 were negative, primarily due to increases in our operating expenditures and other tax rates. Revisions of previous estimates in 2017 were positive, primarily due to the application of both experience and ever improving technology in drilling and completing Haynesville Shale natural gas wells. Well production performance has improved by drilling longer laterals, increasing both the number of frac stages and the amount of sand used in each frac stage.

[2] Extensions and discoveries were positive on an overall basis in all three periods presented, primarily reflecting our successful drilling results on our Haynesville Shale Trend properties.

[3] In 2019, we sold approximately 54,571 Mmcfe and in 2018, we sold approximately 2,500 Mmcfe, attributed to the sale of producing properties in the TMS and Haynesville Shale.