The provision for depreciation has been computed principally by the straight-line method based on the estimated useful lives of the depreciable assets as follows:
Category  Useful Life
Buildings  30 years
Leased assets and leasehold improvements  Amortized over the lesser of the economic life of the asset or the term of the lease
Machinery, equipment and other  
3 – 10 years
The classes of property, plant, and equipment as of December 31 are summarized as follows:
20252024
Land and improvements$35.1 $35.9 
Buildings and leasehold improvements159.5 143.7 
Machinery, equipment and other459.7 424.0 
Gross property, plant and equipment654.3 603.6 
Less: accumulated depreciation(468.7)(437.0)
Construction in progress28.6 33.6 
Property, plant and equipment, net$214.2 $200.2 

About PP&E Disclosures

The PP&E disclosure details a company's physical asset base — land, buildings, machinery, and equipment — along with the depreciation methods and useful life assumptions that determine how these costs flow through the income statement. Capitalization policy thresholds reveal management's judgment on the boundary between expense and asset, directly affecting both reported earnings and asset values.

Key signals: changes in estimated useful lives or depreciation methods can materially shift reported earnings without any operational change. Compare capital expenditures against depreciation expense — when capex consistently trails depreciation, the asset base may be aging and underinvested. Watch for large asset impairments or write-downs that signal overvalued carrying amounts. Asset retirement obligations reveal future environmental or decommissioning costs that are often underappreciated. Compare PP&E intensity (PP&E-to-revenue) against industry peers to assess capital efficiency and competitive positioning.