| **Claim and Claim Adjustment Expense Reserves (International - Hardy - Net Incurred Claims and Allocated Claim Adjustment Expenses) (Details) - Hardy - International $ in Millions** | Dec. 31, 2018 USD ($) claims | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($) | Dec. 31, 2012 USD ($) |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------|-----------------------|-----------------------|-----------------------|-----------------------|-----------------------|-----------------------|
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 1,550                      |                  |                  |                  |                  |                  |                  |
| Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented                                                                               | 456                          |                  |                  |                  |                  |                  |                  |
| IBNR                                                                                                                                                                                  | 185                          |                  |                  |                  |                  |                  |                  |
| 2009                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Net Claim and Claim Adjustment Expense Reserves at Acquisition                                                                                                                        |                         |                  |                  |                  |                  |                  | $ 11                  |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | (3)                          | $ (3)                 | $ (2)                 | $ 1                   | $ (4)                 | $ 6                   | 0                     |
| Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented                                                                               |                         |                  |                  |                  |                  |                  | 12                    |
| IBNR                                                                                                                                                                                  | $ (2)                        |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 3,856                        |                  |                  |                  |                  |                  |                  |
| 2010                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Net Claim and Claim Adjustment Expense Reserves at Acquisition                                                                                                                        |                         |                  |                  |                  |                  |                  | 48                    |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 50                         | 51                    | 52                    | 46                    | 52                    | 47                    | (9)                   |
| Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented                                                                               |                         |                  |                  |                  |                  |                  | 38                    |
| IBNR                                                                                                                                                                                  | $ 0                          |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 4,540                        |                  |                  |                  |                  |                  |                  |
| 2011                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Net Claim and Claim Adjustment Expense Reserves at Acquisition                                                                                                                        |                         |                  |                  |                  |                  |                  | 125                   |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 140                        | 137                   | 137                   | 138                   | 134                   | 134                   | (1)                   |
| Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented                                                                               |                         |                  |                  |                  |                  |                  | 124                   |
| IBNR                                                                                                                                                                                  | $ (2)                        |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 6,252                        |                  |                  |                  |                  |                  |                  |
| 2012                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Net Claim and Claim Adjustment Expense Reserves at Acquisition                                                                                                                        |                         |                  |                  |                  |                  |                  | 33                    |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 115                        | 113                   | 113                   | 119                   | 112                   | 104                   | 71                    |
| Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented                                                                               |                         |                  |                  |                  |                  |                  | $ 104                 |
| IBNR                                                                                                                                                                                  | $ 1                          |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 6,900                        |                  |                  |                  |                  |                  |                  |
| 2013                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 144                        | 140                   | 139                   | 138                   | 146                   | $ 130                 |                  |
| IBNR                                                                                                                                                                                  | $ 4                          |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 7,624                        |                  |                  |                  |                  |                  |                  |
| 2014                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 170                        | 170                   | 176                   | 182                   | $ 184                 |                  |                  |
| IBNR                                                                                                                                                                                  | $ 2                          |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 8,097                        |                  |                  |                  |                  |                  |                  |
| 2015                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 178                        | 177                   | 179                   | $ 190                 |                  |                  |                  |
| IBNR                                                                                                                                                                                  | $ 3                          |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 8,968                        |                  |                  |                  |                  |                  |                  |
| 2016                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 234                        | 245                   | $ 227                 |                  |                  |                  |                  |
| IBNR                                                                                                                                                                                  | $ 28                         |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 9,536                        |                  |                  |                  |                  |                  |                  |
| 2017                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 252                        | $ 244                 |                  |                  |                  |                  |                  |
| IBNR                                                                                                                                                                                  | $ 48                         |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 10,309                       |                  |                  |                  |                  |                  |                  |
| 2018                                                                                                                                                                                  |                         |                  |                  |                  |                  |                  |                  |
| **Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]**                                                                                 |                         |                  |                  |                  |                  |                  |                  |
| Incurred claims and allocated claim adjustment expense, net                                                                                                                           | $ 270                        |                  |                  |                  |                  |                  |                  |
| IBNR                                                                                                                                                                                  | $ 103                        |                  |                  |                  |                  |                  |                  |
| Cumulative Number of Claims | claims                                                                                                                                                  | 7,563                        |                  |                  |                  |                  |                  |                  |

| X                                                                                                                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Net Claim and Claim Adjustment Expense Reserves at Acquisition
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[Line Items] for Net Incurred Claim and Claim Adjustment Expense [Table]
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No definition available.
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| - Definition
Undiscounted amount, after reinsurance, of incurred-but-not-reported (IBNR) liabilities plus expected development on reported claims, for claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense.
+ References
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| - Definition
Undiscounted amount, after reinsurance, of incurred claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense.
+ References
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| - Definition
Cumulative number of reported claims for short-duration insurance contracts.
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