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Summary of Significant Accounting Principles and Practices (Tables) | 12 Months Ended
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Dec. 31, 2017
Accounting Policies [Abstract] |
Schedule of estimated useful lives of assets | Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, which are generally as follows:
Asset Description |  | Expected Life
Software |  | Lesser of the life of an associated license, or 4 to 7 years
Leasehold improvements |  | Lesser of estimated useful life or lease term, not to exceed 10 years
Furniture, fixtures and equipment |  | 4 to 10 years
Computer equipment |  | 4 to 6 years
Buildings |  | 35 years
Automobiles |  | 6 years
Schedule of other intangible assets by asset class | Amortization basis and estimated useful lives by intangible asset type are generally as follows:
Intangible Asset Description |  | Amortization Basis |  | Expected Life
Customer related and contract based |  | In line with underlying cash flows |  | 7 to 20 years
Tradenames |  | Straight-line |  | 1 to 3 years
Technology |  | Straight-line |  | 5 to 7 years
Other intangible assets by asset class are as follows (in millions):
| As of December 31
| 2017 |  | 2016
| Gross Carrying Amount |  | Accumulated Amortization and Impairment |  | Net Carrying Amount |  | Gross Carrying Amount |  | Accumulated Amortization and Impairment |  | Net Carrying Amount
Customer related and contract based | 2,550 |  |  | 1,415 |  |  | 1,135 |  |  | 2,023 |  |  | 1,198 |  |  | 825 |
Tradenames (1) | 1,047 |  |  | 533 |  |  | 514 |  |  | 1,027 |  |  | 7 |  |  | 1,020 |
Technology and other (1) | 416 |  |  | 332 |  |  | 84 |  |  | 347 |  |  | 302 |  |  | 45 |
Total | $ | 4,013 |  |  | $ | 2,280 |  |  | $ | 1,733 |  |  | $ | 3,397 |  |  | $ | 1,507 |  |  | $ | 1,890 |
(1) | Prior to May 1, 2017, finite lived tradenames were classified within Technology and other. As of December 31, 2016, $29 million of gross carrying amount and $7 million of accumulated amortization related to finite-lived tradenames were reclassified from Technology and other to Tradenames.
Schedule of New Accounting Pronouncements and Changes in Accounting Principles | Upon adoption of the guidance, the Company expects the presentation of results to reflect a change in operating income offset by an equal and offsetting change in other income (expense) for each period, as follows:
|  | Years ended December 31
|  | 2017 |  | 2016
|  | As Reported |  | Adjustments (1) |  | As Adjusted |  | As Reported |  | Adjustments (1) |  | As Adjusted
Operating income (2) |  | 979 |  |  | 86 |  |  | 1,065 |  |  | 1,638 |  |  | 173 |  |  | 1,811 |
Other income (expense) |  | (39 | ) |  | (86 | ) |  | (125 | ) |  | 36 |  |  | (173 | ) |  | (137 | )
(1) | The years ended December 31, 2017 and 2016, include non-cash settlement expenses of $128 million and $220 million, respectively, related to certain pension plans. Refer to Note 12 “Employee Benefits” for further information.
(2) | Reclassification from operating income is recorded in Compensation and benefits.

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