Depreciation is provided on a straight-line basis over the estimated useful lives of owned assets. Leasehold improvements and leased properties under capital leases are amortized over the estimated useful life of the property or over the term of the lease, whichever is shorter. Estimated useful lives range from 10 to 39 years for land improvements, buildings and building improvements; and 2 to 13 years for equipment. Major repairs, which extend the useful life of an asset, are capitalized; routine maintenance and repairs are charged against earnings. The majority of the business uses the composite method of depreciation for equipment. Therefore, gains and losses on retirement or other disposition of such assets are included in earnings only when an operating location is closed, completely remodeled or impaired. Fully depreciated property and equipment are removed from the cost and related accumulated depreciation and amortization accounts. Property and equipment consists of (in millions):
| 2014 | | 2013 | Land and land improvements | | | | Owned locations | $ | 3,059 | | $ | 3,203 | Distribution centers | | 93 | | | 97 | Other locations | | 266 | | | 219 | Buildings and building improvements | | | | | | Owned locations | | 3,927 | | | 3,805 | Leased locations (leasehold improvements only) | | 2,041 | | | 1,811 | Distribution centers | | 582 | | | 620 | Other locations | | 351 | | | 351 | Equipment | | | | | | Locations | | 5,454 | | | 5,334 | Distribution centers | | 1,170 | | | 1,190 | Other locations | | 935 | | | 755 | Capitalized system development costs | | 688 | | | 581 | Capital lease properties | | 530 | | | 215 | | | 19,096 | | | 18,181 | Less: accumulated depreciation and amortization | | 6,839 | | | 6,043 | | $ | 12,257 | | $ | 12,138 |
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