Asset retirement obligations (Tables)

3 Months Ended

Mar. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Schedule of asset retirement obligation liability

The following table reconciles the Company's asset retirement obligation liability associated with tangible long-lived assets for the periods presented:

	Three months ended March 31,
(in thousands)	2020			2019
Liability at beginning of period	$	62,718		$	56,882
Liabilities added due to acquisitions, drilling, midstream service asset construction and other	886			271
Accretion expense	1,106			1,052
Liabilities settled due to plugging and abandonment	(497		)	(447		)
Liability at end of period	$	64,213		$	57,758