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Deferred Policy Acquisition Costs - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016
Deferred Policy Acquisition Costs Disclosures [Abstract] |  |
Accumulated amortization of present value of future profits | $ 141 | $ 134
Approximate annual rate of decrease in present value of future profits during next five years | 12.50% |

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- Definition The cumulative amount of amortization of present value of future profits that has been recognized in the Income Statement. + References No definition available. + Details
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