Summary of Significant Accounting Policies - Investment Contract and Life Policy Reserves (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Investment contract reserves	$ 4,675,774	$ 4,555,856
Policy reserves	1,558,678	1,155,337
Total	$ 6,234,452	$ 5,711,193

Amount, before effect of reinsurance, of present value of future benefit to be paid to or on behalf of policyholder and related expense less present value of future net premium receivable under insurance contract.

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Amount of accrued obligation to policyholders that relates to insured events under individual and group annuities and supplementary insurance contracts.

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Amount of accrued obligation to policyholders that relates to insured events under long-term life insurance contracts.

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