PROPERTY, PLANT & EQUIPMENT

12 Months Ended

Dec. 31, 2023

PROPERTY, PLANT & EQUIPMENT [Abstract]

PROPERTY, PLANT & EQUIPMENT

NOTE 4: PROPERTY, PLANT & EQUIPMENT

Balances of major classes of assets and allowances for depreciation, depletion and amortization at December 31 are as follows:

in millions	2023	2022
Property, Plant & Equipment
Land and land improvements 1	$       4,292.6	$      3,991.1
Buildings	204.4	223.3
Machinery and equipment	6,785.5	6,454.2
Finance leases (see Note 7)	62.3	93.2
Deferred asset retirement costs	171.3	165.9
Construction in progress	319.4	378.7
Total, gross	$     11,835.5	$    11,306.4
Less allowances for depreciation, depletion
and amortization	5,617.8	5,255.1
Total, net	$       6,217.7	$      6,051.3

¹ Includes depletable land as follows: December 31, 2023 — $2,684.4 million and December 31, 2022 — $2,445.6 million.

Capitalized interest costs with respect to qualifying construction projects and total interest costs incurred before recognition of the capitalized amount for the years ended December 31 are as follows:

in millions	2023	2022	2021
Capitalized interest cost	$             3.7	$            3.6	$            4.2
Total interest cost incurred before recognition
of the capitalized amount	199.8	172.8	153.5

Capitalized software costs of $13.1 million and $10.1 million are reflected in net property, plant & equipment as of December 31, 2023 and 2022, respectively. We capitalized software costs for the years ended December 31 as follows: 2023 — $9.6 million, 2022 — $2.7 million and 2021 — $2.7 million.