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Claim and Claim Adjustment Expense Reserves (International - Hardy - Net Incurred Claims and Allocated Claim Adjustment Expenses) (Details) - Hardy - International $ in Millions | Dec. 31, 2017 USD ($) claims | Dec. 31, 2016 USD ($) | 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 | $ 1,309 |  |  |  |  |
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented | 393 |  |  |  |  |
IBNR | 175 |  |  |  |  |
2008 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Net Claim and Claim Adjustment Expense Reserves at Acquisition |  |  |  |  |  | $ 18
Incurred claims and allocated claim adjustment expense, net | 13 | $ 12 | $ 13 | $ 13 | $ 11 | (3)
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented |  |  |  |  |  | 15
IBNR | $ 1 |  |  |  |  |
Cumulative Number of Claims | claims | 4,237 |  |  |  |  |
2009 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Net Claim and Claim Adjustment Expense Reserves at Acquisition |  |  |  |  |  | 12
Incurred claims and allocated claim adjustment expense, net | $ (3) | (2) | 1 | (4) | 7 | 0
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented |  |  |  |  |  | 12
IBNR | $ 0 |  |  |  |  |
Cumulative Number of Claims | claims | 3,852 |  |  |  |  |
2010 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Net Claim and Claim Adjustment Expense Reserves at Acquisition |  |  |  |  |  | 49
Incurred claims and allocated claim adjustment expense, net | $ 52 | 53 | 47 | 53 | 48 | (10)
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented |  |  |  |  |  | 39
IBNR | $ (1) |  |  |  |  |
Cumulative Number of Claims | claims | 4,524 |  |  |  |  |
2011 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Net Claim and Claim Adjustment Expense Reserves at Acquisition |  |  |  |  |  | 126
Incurred claims and allocated claim adjustment expense, net | $ 140 | 140 | 140 | 136 | 136 | 0
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented |  |  |  |  |  | 126
IBNR | $ (2) |  |  |  |  |
Cumulative Number of Claims | claims | 6,228 |  |  |  |  |
2012 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Net Claim and Claim Adjustment Expense Reserves at Acquisition |  |  |  |  |  | 34
Incurred claims and allocated claim adjustment expense, net | $ 115 | 114 | 121 | 113 | 106 | 71
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented |  |  |  |  |  | $ 105
IBNR | $ (1) |  |  |  |  |
Cumulative Number of Claims | claims | 6,863 |  |  |  |  |
2013 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 142 | 141 | 140 | 148 | $ 133 |
IBNR | $ 1 |  |  |  |  |
Cumulative Number of Claims | claims | 7,525 |  |  |  |  |
2014 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 172 | 179 | 185 | $ 187 |  |
IBNR | $ (2) |  |  |  |  |
Cumulative Number of Claims | claims | 7,954 |  |  |  |  |
2015 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 180 | 182 | $ 192 |  |  |
IBNR | $ 9 |  |  |  |  |
Cumulative Number of Claims | claims | 8,578 |  |  |  |  |
2016 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 251 | $ 232 |  |  |  |
IBNR | $ 53 |  |  |  |  |
Cumulative Number of Claims | claims | 8,443 |  |  |  |  |
2017 |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 247 |  |  |  |  |
IBNR | $ 117 |  |  |  |  |
Cumulative Number of Claims | claims | 6,508 |  |  |  |  |

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