Supplemental Oil and Gas Disclosures (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Oil and Gas Exploration and Production Industries Disclosures [Abstract]

Results of Operations for Producing Activities Table

	Year Ended December 31,
	2017			2016			2015
	(In Thousands)
Oil and gas sales revenues	$	538		$	751		$	2,438
Production (lifting) costs	1,234			643			921
Excess decommissioning and abandonment costs	—			2,593			2,665
Accretion expense	1,382			1,362			1,375
Pretax income (loss) from producing activities	(2,078		)	(3,847		)	(2,523		)
Income tax expense (benefit)	—			—			—
Results of oil and gas producing activities	$	(2,078	)	$	(3,847	)	$	(2,523	)