Land, buildings and equipment, net were as follows:
December 31,
 Estimated Useful Lives (Years)20242023
Land$$
Building and building equipment
25 to 50
669 678 
Leasehold improvements
1 to 12
72 78 
Plant machinery
5 to 12
771 855 
Office furniture and equipment
3 to 15
411 436 
Finance leased assets
1 to 12
79 33 
Other
4 to 20
35 37 
Construction in progress11 11 
Subtotal 2,056 2,136 
Accumulated depreciation(1)
 (1,805)(1,870)
Land, buildings and equipment, net $251 $266 
_____________
(1)Depreciation expense was $57, $60 and $68 for the three years ended December 31, 2024, 2023 and 2022, respectively.

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.