Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Schedule of change in asset retirement obligation

During 2020 and 2019, our overall asset retirement obligation changed as follows (in thousands):

	2020		2019
Beginning balance	$	91,251	$	69,350
Accretion	5,410		4,605
Changes in estimates of existing obligations (1)	(884)		17,307
Property dispositions/obligations settled	—		(11)
Ending balance	$	95,777	$	91,251

(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 decrease in 2020 is primarily due to a decrease in the inflation rate and an increase in the estimated remaining life of the ARO assets.