| **Hardy (Narrative) (Details) (USD $)In Millions, unless otherwise specified**      | 3 Months Ended | 9 Months Ended |        | 3 Months Ended | 9 Months Ended | 12 Months Ended |        |
|-------------------------------------------------------------------------------------|----------------|----------------|--------|----------------|----------------|-----------------|--------|
||
| **Business Acquisition [Line Items]**                                               |           |           |   |           |           |            |   |   |   |
| Gross written premiums                                                              |           |           |   |           |           |            |   | $ 430 |   |
| Net income (loss) in accordance with IFRS                                           |           |           |   |           |           |            |   | (55) |   |
| Business acquisition, cost of acquired entity, purchase price                       |           |           |   |           |           |            |   |   | 231 |
| Business combination, acquisition related costs                                     |           |           |   |           |           |            | 4      |   |   |
| Amortization of deferred acquisition costs                                          | 333            | 297            | 937    | 880            |           | 18              |   |   |   |
| Amortization expense included in other expenses                                     |           |           |   |           |           | 6               |   |   |   |
| Future Amortization Expense, Remainder of Fiscal Year                               |           |           |   |           |           |            | 19     |   |   |
| Future amortization expense, year one                                               |           |           |   |           |           |            | 21     |   |   |
| Future amortization expense, year two                                               |           |           |   |           |           |            | 4      |   |   |
| Future amortization expense, year three                                             |           |           |   |           |           |            | 1      |   |   |
| Future amortization expense, year four                                              |           |           |   |           |           |            | 2      |   |   |
| Future amortization expense, year five                                              |           |           |   |           |           |            | 2      |   |   |
| Business Acquisition, Purchase Price Allocation, Goodwill Amount                    |           |           |   |           | 35             |            |   |   |   |
| Carrying value of funds at Lloyd's                                                  | 66             |           | 66     |           |           |            |   |   |   |
| Carrying Value Of Securities Deposited Under Requirements Of Regulatory Authorities |           |           |   |           |           | $ 71            | $ 71   |   |   |

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Carrying value of funds at Lloyd's
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Gross written premiums written by Hardy
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Hardy net loss determined in accordance with International Financial Reporting Standards (IFRS)
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.
+ References
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| - Definition
Amount of goodwill arising from a business combination, which is the excess of the cost of the acquired entity over the amounts assigned to assets acquired and liabilities assumed.
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| - Definition
This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.
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| - Definition
Amount of deferred policy acquisition costs charged to expense in the period, generally in proportion to related revenue earned, estimated gross profits, or over the customer relationship or some other period.
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The amount of amortization expense expected to be recognized during the remainder of the current fiscal year.
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| - Definition
The amount of amortization expense expected to be recognized during year five of the five succeeding fiscal years.
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| - Definition
The amount of amortization expense expected to be recognized during year four of the five succeeding fiscal years.
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| - Definition
The amount of amortization expense expected to be recognized during year one of the five succeeding fiscal years.
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| - Definition
The amount of amortization expense expected to be recognized during year three of the five succeeding fiscal years.
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| - Definition
The amount of amortization expense expected to be recognized during year two of the five succeeding fiscal years.
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