Note 5 - Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2019

Asset Retirement Obligation Disclosure [Abstract]

Amounts recorded related to asset retirement obligations

	Year Ended December 31,
(In thousands)	2019		2018
Balance at beginning of year	$	12,778	$	12,347
Additional asset retirement obligations acquired/incurred		800		131
Accretion expense		511		494
Revisions to estimates		516		(194)
Balance at end of year	$	14,605	$	12,778