PROPERTY, PLANT, AND EQUIPMENT

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property, plant, and equipment consisted of the following at December 31:


(in millions)	2023		2022
Electric – generation	$	3,108.8	$	2,736.5
Electric – distribution	2,338.5		2,184.9
Natural gas – distribution, storage, and transmission	1,266.3		1,184.5
Property, plant, and equipment to be retired, net	259.8		273.1
Other	513.3		493.1
Less: Accumulated depreciation	1,857.8		1,662.6
Net	5,628.9		5,209.5
CWIP	172.5		167.2
Total property, plant, and equipment	$	5,801.4	$	5,376.7

Severance Liability for Plant Retirements

We have severance liabilities related to past and future plant retirements recorded in other current and other long-term liabilities on our balance sheets. Activity related to these severance liabilities for the years ended December 31 was as follows:


(in millions)	2023		2022		2021
Severance liability at January 1	$	2.7	$	1.6	$	—
Severance expense	—		1.1		1.6


Total severance liability at December 31	$	2.7	$	2.7	$	1.6

Plant to be Retired

Columbia Units 1 and 2

As a result of a MISO ruling received in June 2021, retirement of the jointly-owned Columbia Units 1 and 2 became probable. Columbia Units 1 and 2 are expected to be retired by June 2026. The total net book value of our ownership share of Columbia Units 1 and 2 was $259.8 million at December 31, 2023, which does not include deferred taxes. This amount was classified as plant to be retired within property, plant, and equipment on our balance sheet. These units are included in rate base, and we continue to depreciate them on a straight-line basis using the composite depreciation rates approved by the PSCW.