PROPERTY AND DEPRECIATION

We provide for depreciation and amortization using the straight-line method over the following estimated useful asset lives:



Classification	Estimated Useful Asset Life
Buildings	42 years
Leasehold improvements	Over the shorter of the asset’s life or the lease term
Furniture, fixtures, equipment and software	3 to 14 years
Assets held under capital leases	Over the shorter of the asset’s life or the lease term

Depreciation expense was $39,332, $38,588, and $35,040 in 2016, 2015, and 2014, respectively.

At the time property is retired or otherwise disposed of, the asset and related accumulated depreciation are removed from the accounts, and any resulting gain or loss is credited or charged to other income, net.

Assets held under capital leases, consisting primarily of information technology equipment, are recorded in property with the corresponding obligations carried in long-term debt. The amount capitalized is the present value at the beginning of the lease term of the aggregate future minimum lease payments. Assets held under leases which were capitalized during the year ended December 31, 2016 and 2015 were $427 and $7,354, respectively.

We capitalize interest expense on major construction and development projects while in progress. There was no interest capitalized in 2016. Interest capitalized in 2015 and 2014 was $225 and $102, respectively.

Where applicable, we will capitalize qualifying internal and external costs incurred to develop or obtain software for internal use during the application development stage. Costs incurred during the pre-application development and post-implementation stages are expensed as incurred. We capitalized software and software development costs of $3,542 and $4,559 in 2016 and 2015, respectively, and the amounts are recorded in furniture and fixtures.

We consider properties to be assets held for sale when all of the following criteria are met: (i) a formal commitment to a plan to sell a property has been made and exercised; (ii) the property is available for sale in its present condition; (iii) actions required to complete the sale of the property have been initiated; (iv) sale of the property is probable and we expect the sale will occur within one year; and (v) the property is being actively marketed for sale at a price that is reasonable given its current market value.

Upon designation as an asset held for sale, we record the carrying value of each property at the lower of its carrying value or its estimated fair value, less estimated costs to sell, and depreciation of the property ceases. The net book value of assets held for sale was $464 and $58 at December 31, 2016 and 2015, respectively, and is recorded in net property in the consolidated balance sheet. During 2016 and 2015, we sold assets classified as held for sale with net book values of $148 and $7,669, respectively, and recorded net gains on the assets held for sale of $2,004 and $4,691, respectively in other income, net.

We review long-lived assets held and used for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. For assets classified as to be held and used, impairment may occur if projected undiscounted cash flows are not adequate to cover the carrying value of the assets. In such cases, additional analysis is conducted to determine the amount of the loss to be recognized. The impairment loss is calculated as the difference between the carrying amount of the asset and its estimated fair value. The analysis requires estimates of the amount and timing of projected cash flows and, where applicable, selection of an appropriate discount rate. Such estimates are critical in determining whether any impairment charge should be recorded and the amount of such charge if an impairment loss is deemed necessary.

For assets held for sale, impairment occurs whenever the net book value of the property listed for sale exceeds the expected selling price less estimated selling expenses. There were no impairment charges recorded during 2016 and 2015.