Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2021

Asset Retirement Obligation Disclosure [Abstract]

Schedule of changes in asset retirement obligation

During 2021 and 2020, our overall asset retirement obligation changed as follows (in thousands): 

	2021		2020
Beginning balance	$	450,501	$	459,209
Accretion	22,343		23,142
New obligations	1,249		1,154
Changes in estimates of existing obligations (1)	59,460		(21,889)
Property dispositions/obligations settled	(15,166)		(11,115)
Ending balance	$	518,387	$	450,501

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(1)    Changes in estimates of existing obligations are primarily due to the annual review process, which considers various factors including inflation rate, current estimates for removal costs, discount rates, and the estimated remaining life of assets. The increase in 2021 is primarily due to an increase in estimated removal cost for offshore AROs. The decrease in 2020 is primarily due to a decrease in the inflation rate.