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Restructuring - Narrative (Details) - 2017 Plan $ in Millions | 3 Months Ended | 27 Months Ended
--- | --- | ---
Mar. 31, 2019 USD ($) job_elimination | Dec. 31, 2018 USD ($) | Mar. 31, 2019 USD ($) job_elimination
Restructuring Cost and Reserve [Line Items] |  |  |
Additional expected cost |  | $ 200 |
Additional expected cash investment |  | 150 |
Additional expected non-cash expense |  | $ 50 |
Expected total cost | $ 1,225 |  | $ 1,225
Number of positions eliminated to date | job_elimination |  |  | 4,491
Costs incurred | 91 |  | $ 1,073
Workforce reduction |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Expected total cost | 450 |  | 450
Costs incurred | 24 |  | 438
Technology rationalization |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Expected total cost | 130 |  | 130
Costs incurred | 11 |  | 91
Lease consolidation |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Expected total cost | 65 |  | 65
Costs incurred | 9 |  | 45
Asset impairments |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Expected total cost | 50 |  | 50
Costs incurred | 0 |  | 39
Other Restructuring |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Expected total cost | 530 |  | 530
Costs incurred | $ 47 |  | $ 460
Minimum |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Expected number of positions eliminated | job_elimination | 4,800 |  |
Maximum |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Expected number of positions eliminated | job_elimination | 5,400 |  |

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