Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Measurements

Summary of Financial Assets and Liabilities Accounted for at Fair Value

	December 31, 2023
	Total		Level 1		Level 2		Level 3
	(In thousands)
Assets:
Investments in marketable securities	$	32,724	$	28,773	$	3,951	$	—
Derivatives		998		—		—		998
Fund for asset retirement obligations		142,266		142,266		—		—
Total assets	$	175,988	$	171,039	$	3,951	$	998
Liabilities:
Derivatives	$	165	$	—	$	165	$	—

	Fair Value at December 31, 2022
	Total		Level 1		Level 2		Level 3
	(In thousands)
Assets:
Investments in marketable securities	$	36,993	$	28,301	$	8,692	$	—
Derivatives		3,955		—		2,655		1,300
Fund for asset retirement obligations		135,993		135,993		—		—
Total assets	$	176,941	$	164,294	$	11,347	$	1,300
Liabilities:
Derivatives	$	—	$	—	$	—	$	—

Summary of Change in the Fair Values of Financial Instruments Categorized as Level 3

	2023		2022
(In thousands)
Balance, beginning of period	$	1,300	$	1,219
Realized and unrealized gains (losses) recognized in earnings, net		(4,192)		7,019
Purchases		5,400		4,673
Settlements		(1,510)		(11,611)
Ending balance	$	998	$	1,300