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Acquisitions and Divestitures - Merger and Integration Expenses (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2021 | Mar. 31, 2020
Business Acquisition [Line Items] |  |
Merger and integration expense | $ 70 | $ 6
Personal expense |  |
Business Acquisition [Line Items] |  |
Merger and integration expense | 21 | 1
Legal and professional fees |  |
Business Acquisition [Line Items] |  |
Merger and integration expense | 3 | 2
Net occupancy expense |  |
Business Acquisition [Line Items] |  |
Merger and integration expense | 3 | 0
Other expense |  |
Business Acquisition [Line Items] |  |
Merger and integration expense | $ 43 | $ 3

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- Definition Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs. + References No definition available. + Details
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