ASSET RETIREMENT OBLIGATIONS (Tables)

12 Months Ended

Dec. 31, 2022

ASSET RETIREMENT OBLIGATIONS [Abstract]

Asset Retirement Obligations Operating Costs

in millions	2022	2021	2020
ARO Operating Costs
Accretion	$         14.1	$         13.1	$         12.4
Depreciation	9.4	10.6	8.6
Total	$         23.5	$         23.7	$         21.0

Reconciliations of Asset Retirement Obligations

in millions	2022	2021
Asset Retirement Obligations
Balance at beginning of year	$       315.2	$       283.2
Liabilities incurred	8.2	19.2
Liabilities settled	(8.8)	(11.0)
Accretion expense	14.1	13.1
Revisions, net	(17.4)	10.7
Balance at end of year	$       311.3	$       315.2