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SCHEDULE II - Condensed Financial Information Of Registrant Condensed Financial Information Of Registrant - Additional Information (Detail) - USD ($) $ in Billions | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Apr. 01, 2015
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Significant Accounting Policies [Line Items] |  |  |  |
Securities Held In Consolidated Non-Insurance Subsidiary | $ 1.6 | $ 1.3 |  |
ARX Holding Corp. |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Equity interest percentage | 69.00% | 69.20% | 69.20% | 5.00%
Parent Company |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |
Securities Held In Consolidated Non-Insurance Subsidiary | $ 1.6 | $ 1.3 |  |

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- Definition Securities held in the portfolio of a consolidated, non-insurance subsidiary of the holding company, net of any unsettled security transactions. + References No definition available. + Details
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- Definition Significant Accounting Policies [Line Items] + References No definition available. + Details
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- Definition Percentage of voting equity interests acquired in a business combination achieved in stages, including equity interests in the acquiree held by the acquirer immediately before the acquisition date and acquired at the acquisition date. + References No definition available. + Details
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- Details
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- Details
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