ASSET RETIREMENT OBLIGATIONS (Tables)

9 Months Ended

Sep. 30, 2018

ASSET RETIREMENT OBLIGATIONS [Abstract]

Asset Retirement Obligations Operating Costs

	Three Months Ended		Nine Months Ended
	September 30		September 30
in thousands	2018	2017	2018	2017
ARO Operating Costs
Accretion	$        2,684	$        2,857	$        8,036	$        8,620
Depreciation	1,512	1,494	4,192	4,741
Total	$        4,196	$        4,351	$      12,228	$      13,361

Reconciliations of Asset Retirement Obligations

	Three Months Ended		Nine Months Ended
	September 30		September 30
in thousands	2018	2017	2018	2017
Asset Retirement Obligations
Balance at beginning of period	$     215,421	$     223,953	$     218,117	$     223,872
Liabilities incurred	0	731	0	1,066
Liabilities settled	(2,649)	(5,263)	(10,476)	(15,739)
Accretion expense	2,684	2,857	8,036	8,620
Revisions, net	10,628	610	10,407	5,069
Balance at end of period	$     226,084	$     222,888	$     226,084	$     222,888