ASSET RETIREMENT OBLIGATIONS (Tables)

6 Months Ended

Jun. 30, 2018

ASSET RETIREMENT OBLIGATIONS [Abstract]

Asset Retirement Obligations Operating Costs

	Three Months Ended		Six Months Ended
	June 30		June 30
in thousands	2018	2017	2018	2017
ARO Operating Costs
Accretion	$        2,668	$        2,881	$        5,352	$        5,763
Depreciation	1,343	1,615	2,680	3,247
Total	$        4,011	$        4,496	$        8,032	$        9,010

Reconciliations of Asset Retirement Obligations

	Three Months Ended		Six Months Ended
	June 30		June 30
in thousands	2018	2017	2018	2017
Asset Retirement Obligations
Balance at beginning of period	$     214,709	$     226,012	$     218,117	$     223,872
Liabilities incurred	0	335	0	335
Liabilities settled	(1,805)	(5,610)	(7,826)	(10,475)
Accretion expense	2,668	2,881	5,352	5,763
Revisions, net	(151)	335	(222)	4,458
Balance at end of period	$     215,421	$     223,953	$     215,421	$     223,953