ASSET RETIREMENT OBLIGATIONS (Tables)

3 Months Ended

Mar. 31, 2023

ASSET RETIREMENT OBLIGATIONS [Abstract]

Asset Retirement Obligations Operating Costs

	Three Months Ended
	March 31
in millions	2023	2022
ARO Operating Costs
Accretion	$          3.4	$          3.5
Depreciation	2.2	2.4
Total	$          5.6	$          5.9

Reconciliations of Asset Retirement Obligations

	Three Months Ended
	March 31
in millions	2023	2022
Asset Retirement Obligations
Balance at beginning of year	$       311.3	$       315.2
Liabilities incurred	0.0	2.3
Liabilities settled	(2.9)	(1.3)
Accretion expense	3.4	3.5
Revisions, net	0.1	0.0
Balance at end of period	$       311.9	$       319.7