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Derivatives - Narrative (Details) £ in Billions |  | 1 Months Ended | 3 Months Ended | 9 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Sep. 20, 2018 GBP (£) | Jan. 31, 2019 USD ($) | Mar. 31, 2019 USD ($) | Sep. 30, 2020 USD ($) | Sep. 30, 2019 USD ($) | Sep. 30, 2020 EUR (€) | Mar. 31, 2019 EUR (€) | Dec. 31, 2018 USD ($)
Derivative [Line Items] |  |  |  |  |  |  |  |
Net investment hedge, threshold percentage of the equity balance |  |  |  | 80.00% |  |  |  |
Increase in net investment hedges |  |  |  | $ 60,000,000 |  |  |  |
Total consideration |  |  |  | $ 742,000,000 | $ 5,925,000,000 |  |  |
Net Investment Hedging |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |
Derivative, notional amount | € |  |  |  |  |  | € 1,100,000,000 |  |
Senior Notes |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |
Debt instrument face amount |  | $ 5,000,000,000 |  |  |  |  |  |
Foreign Exchange Forward |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |
Unrealized gain |  |  |  |  | 31,000,000 |  |  |
Treasury Lock |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |
Payments for derivative settlement |  | $ 122,000,000 | $ 6,000,000 |  |  |  |  |
Jardine Lloyd Thompson Group plc |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |
Total consideration | £ | £ 5.2 |  |  |  |  |  |  |
Jardine Lloyd Thompson Group plc | Senior Notes |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |
Debt instrument face amount | € |  |  |  |  |  |  | € 1,100,000,000 |
Payments for derivative settlement |  |  |  |  | 7,300,000 |  |  |
Jardine Lloyd Thompson Group plc | Foreign Exchange Forward |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |
Derivative, loss on derivative |  |  |  |  | $ 26,000,000 |  |  |
Jardine Lloyd Thompson Group plc | Treasury Lock |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |
Derivative hedges, assets |  |  |  |  |  |  |  | $ 2,000,000,000

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