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Restructuring Narrative (Details) - 2017 Plan $ in Millions | 3 Months Ended | 15 Months Ended
--- | --- | ---
Mar. 31, 2018 USD ($) job_elimination | Mar. 31, 2018 USD ($) job_elimination
Restructuring Cost and Reserve [Line Items] |  |
Expected total cost | $ 1,025 | $ 1,025
Number of positions eliminated to date | job_elimination |  | 3,123
Costs incurred | 74 | $ 571
Workforce reduction |  |
Restructuring Cost and Reserve [Line Items] |  |
Expected total cost | 450 | 450
Costs incurred | 33 | 332
Technology rationalization |  |
Restructuring Cost and Reserve [Line Items] |  |
Expected total cost | 130 | 130
Costs incurred | 10 | 43
Lease consolidation |  |
Restructuring Cost and Reserve [Line Items] |  |
Expected total cost | 85 | 85
Costs incurred | 3 | 11
Asset impairments |  |
Restructuring Cost and Reserve [Line Items] |  |
Expected total cost | 50 | 50
Costs incurred | 1 | 27
Other Restructuring |  |
Restructuring Cost and Reserve [Line Items] |  |
Expected total cost | 310 | 310
Costs incurred | $ 27 | $ 158
Minimum |  |
Restructuring Cost and Reserve [Line Items] |  |
Expected number of positions eliminated | job_elimination | 4,200 |
Maximum |  |
Restructuring Cost and Reserve [Line Items] |  |
Expected number of positions eliminated | job_elimination | 4,800 |

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