Asset Retirement Obligations (Tables)

3 Months Ended

Mar. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Change in asset retirement obligations

The following schedule shows the change in our asset retirement obligations for the three months ended March 31, 2020 (dollars in thousands): 

	2020
Asset retirement obligations at January 1, 2020	$	657,218
Changes attributable to:
Accretion expense	10,219
Settlements	(2,295		)
Estimated cash flow revisions	(5,821		)
Asset retirement obligations at March 31, 2020	$	659,321