ASSET RETIREMENT OBLIGATIONS (Tables)

3 Months Ended

Mar. 31, 2018

ASSET RETIREMENT OBLIGATIONS [Abstract]

Asset Retirement Obligations Operating Costs

	Three Months Ended
	March 31
in thousands	2018	2017
ARO Operating Costs
Accretion	$        2,684	$        2,882
Depreciation	1,337	1,632
Total	$        4,021	$        4,514

Reconciliations of Asset Retirement Obligations

	Three Months Ended
	March 31
in thousands	2018	2017
Asset Retirement Obligations
Balance at beginning of year	$     218,117	$     223,872
Liabilities incurred	0	0
Liabilities settled	(6,021)	(4,865)
Accretion expense	2,684	2,882
Revisions, net	(71)	4,123
Balance at end of period	$     214,709	$     226,012