Property and Equipment
We account for property and equipment at cost less accumulated depreciation and amortization. We compute depreciation using the straight-line method over the estimated useful lives of the assets, generally two to five years. We depreciate buildings over periods up to 25 years. We amortize leasehold improvements over the shorter of the remaining lease term or the estimated useful lives of the assets. Construction in progress is related to the construction or development of property (including land) and equipment that have not yet been placed in service for our intended use. Depreciation for equipment commences once it is placed in service and depreciation for buildings and leasehold improvements commences once they are ready for our intended use. Land is not depreciated.