Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2021

Asset Retirement Obligation Disclosure [Abstract]

Asset Retirement Obligations Table

The following table provides a summary of changes in asset retirement obligations:

	Year Ended December 31,
thousands	2021		2020
Carrying amount of asset retirement obligations at beginning of year	$	280,498	$	358,868
Liabilities incurred	23,923		9,565
Liabilities settled	(12,710)		(20,418)
Accretion expense	12,664		15,070
Revisions in estimated liabilities	3,834		(82,587)
Carrying amount of asset retirement obligations at end of year	$	308,209	$	280,498