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Investment Securities (Net Investment Income) (Details) link:presentationLink link:calculationLink link:definitionLink 2405403 - Disclosure - Investment Securities (Net Realized and Unrealized Investment Gains (Losses) (Details) link:presentationLink link:calculationLink link:definitionLink 2405404 - Disclosure - Investment Securities (Net Realized Investment Gains (Losses)) (Details) link:presentationLink link:calculationLink link:definitionLink 2405405 - Disclosure - Investment Securities (Net Unrealized Investment Gains (Losses)) (Details) link:presentationLink link:calculationLink link:definitionLink 2405421 - Disclosure - Investment Securities (Non-agency Commercial Mortgage-backed Securities) (Details) link:presentationLink link:calculationLink link:definitionLink 2405419 - Disclosure - Investment Securities (Non-agency Mortgage-backed Securities) (Details) link:presentationLink link:calculationLink link:definitionLink 2405420 - Disclosure - Investment Securities (Non-agency Residential Mortgage-backed Securities) (Details) link:presentationLink link:calculationLink link:definitionLink 2405409 - Disclosure - Investment Securities (Other long-term investments) (Details) link:presentationLink link:calculationLink link:definitionLink 2405412 - Disclosure - Investment Securities (Restrictions on Redemption Frequency and Advance Notice Requirements) (Details) link:presentationLink link:calculationLink link:definitionLink 2405423 - Disclosure - Investment Securities (Significant Unobservable Inputs) (Details) link:presentationLink link:calculationLink link:definitionLink 2305301 - Disclosure - Investment Securities (Tables) link:presentationLink link:calculationLink link:definitionLink 2112100 - Disclosure - Investments in Unconsolidated Affiliates link:presentationLink link:calculationLink link:definitionLink 2412402 - Disclosure - Investments in Unconsolidated Affiliates (Details) link:presentationLink link:calculationLink link:definitionLink 2412405 - Disclosure - Investments in Unconsolidated Affiliates (Hamer) (Details) link:presentationLink link:calculationLink link:definitionLink 2412404 - Disclosure - Investments in Unconsolidated Affiliates (Investments in Symetra) (Details) link:presentationLink link:calculationLink link:definitionLink 2412403 - Disclosure - Investments in Unconsolidated Affiliates (Symetra) (Details) link:presentationLink link:calculationLink link:definitionLink 2312301 - Disclosure - Investments in Unconsolidated Affiliates (Tables) link:presentationLink link:calculationLink link:definitionLink 2103100 - Disclosure - Loss and Loss Adjustment Expense Reserves link:presentationLink link:calculationLink link:definitionLink 2403403 - Disclosure - Loss and Loss Adjustment Expense Reserves Details (Details) link:presentationLink link:calculationLink link:definitionLink 2403402 - Disclosure - Loss and Loss Adjustment Expense Reserves (Loss and Loss Adjustment Expense) (Details) link:presentationLink link:calculationLink link:definitionLink 2303301 - Disclosure - Loss and Loss Adjustment Expense Reserves (Tables) link:presentationLink link:calculationLink link:definitionLink 2109100 - 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Disclosure - Third Party Reinsurance (Sirius Group) (Details) link:presentationLink link:calculationLink link:definitionLink