Property, Plant, and Equipment
Property, plant, and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over estimated useful lives of 10 to 40 years for buildings, 3 to 10 years for machinery and equipment, and 10 to 20 years, not to exceed the lease term, for leasehold improvements. Tools, dies, and molds are amortized using the straight-line method over 3 years. Estimated useful lives are periodically reviewed and, where appropriate, changes are made prospectively. The carrying value of property, plant, and equipment is reviewed when events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. Any potential impairment identified is assessed by evaluating the operating performance and future undiscounted cash flows of the underlying assets. When property is sold or retired, the cost of the property and the related accumulated depreciation are removed from the consolidated balance sheet and any resulting gain or loss is included in the results of operations.
PROPERTY AND EQUIPMENT
The following table details the composition of our property and equipment balances:
($ in millions) At Year-End
2010 At Year-End
Land $514 $454
Buildings and leasehold improvements 854 935
Furniture and equipment 984 996
Construction in progress 204 163
Accumulated depreciation (1,249) (1,186)
We record property and equipment at cost, including interest and real estate taxes incurred during development and construction. Interest capitalized as a cost of property and equipment totaled $10 million in 2010, $8 million in 2009, and $26 million in 2008. We capitalize the cost of improvements that extend the useful life of property and equipment when incurred. These capitalized costs may include structural costs, equipment, fixtures, floor, and wall coverings. We expense all repair and maintenance costs as incurred. We compute depreciation using the straight-line method over the estimated useful lives of the assets (three to 40 years), and we amortize leasehold improvements over the shorter of the asset life or lease term. Depreciation expense totaled $138 million in 2010, $151 million in 2009, and $155 million in 2008.
In the 2010 fourth quarter, we determined that we would not be able to fully recover the carrying amount of a capitalized software asset from an existing group of property owners. In accordance with the guidance for the impairment of long-lived assets, we evaluated the asset for recovery and as a result of a negotiated agreement with the property owners, in 2010 we recorded an impairment charge of $84 million to adjust the carrying value of the asset to our estimate of its fair value. We estimated that fair value using an income approach reflecting internally developed Level 3 discounted cash flows that included, among other things, our expectations of future cash flows based on historical experience and projected growth rates, usage estimates and demand trends. The impairment charge impacted the general, administrative, and other expense line in our Income Statement. We did not allocate that charge to any of our segments. In the 2010 fourth quarter, we decided to pursue the disposition of a golf course and related assets from our Timeshare segment. In accordance with the guidance for the impairment of long-lived assets, we evaluated the property and related assets for recovery and in 2010 we recorded an impairment charge of $13 million to adjust the carrying value of the assets to our estimate of fair value. We estimated that fair value using an income approach reflecting internally developed Level 3 discounted cash flows based on negotiations with a...