| **Acquisition - Narrative (Details) - Cincinnati Global £ in Millions, $ in Millions** | Feb. 28, 2019 USD ($) | Feb. 28, 2019 GBP (£) |
|---------------------------------------------------------------------------------------------|-----------------------|----------------------------|
| **Business Acquisition**                                                                    |                  |                       |
| Aggregate consideration paid                                                                | $ 64                  | £ 48                  |
| Broker Relationships And Internally Developed Technology | Minimum                          |                  |                       |
| **Business Acquisition**                                                                    |                  |                       |
| Useful life                                                                                 | 5 years               | 5 years                    |
| Broker Relationships And Internally Developed Technology | Maximum                          |                  |                       |
| **Business Acquisition**                                                                    |                  |                       |
| Useful life                                                                                 | 15 years              | 15 years                   |

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| - Definition
Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
+ References
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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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| - Definition
The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.
+ References
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| X                                                                                                                                                         |
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| X                                                                                                                       |
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| X                                                                                                                       |
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