Fair Value of Assets and Liabilities (Quantitative Info for Level 3 Inputs) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Corporate securities	$ 53,892	$ 63,647
Policyholders’ account balances	7,708,608	6,180,359
Fair Value, Measurements, Recurring
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Future policy benefits	21,325,619	11,822,998
Policyholders’ account balances	$ 303,060	196,892
Level 3 \| Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Policyholder Age	45 years
Level 3 \| Minimum \| Future policy benefits
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Mortality rate	0.00%
Level 3 \| Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Policyholder Age	90 years
Level 3 \| Fair Value, Measurements, Recurring
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Future policy benefits	$ 21,325,619	11,822,998
Policyholders’ account balances	$ 303,060	$ 196,892
Level 3 \| Internal \| Minimum \| Discounted cash flow \| Future policy benefits
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Lapse rate	1.00%	1.00%
Spread over LIBOR	0.09%	0.10%
Utilization rate	39.00%	43.00%
Withdrawal rate (greater than maximum range)	76.00%	78.00%
Mortality rate	0.00%	0.00%
Equity volatility curve	18.00%	13.00%
Level 3 \| Internal \| Minimum \| Discounted cash flow \| Policyholders' account balances
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Lapse rate	1.00%	1.00%
Spread over LIBOR	0.09%	0.10%
Equity volatility curve	6.00%	6.00%
Level 3 \| Internal \| Minimum \| Discounted cash flow \| Corporate securities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate	1.30%	4.79%
Level 3 \| Internal \| Minimum \| Market comparables \| Corporate securities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
EBITDA multiples		6.7
Level 3 \| Internal \| Maximum \| Discounted cash flow \| Future policy benefits
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Lapse rate	20.00%	18.00%
Spread over LIBOR	1.59%	1.23%
Utilization rate	96.00%	97.00%
Withdrawal rate (greater than maximum range)	100.00%	100.00%
Mortality rate	15.00%	15.00%
Equity volatility curve	26.00%	23.00%
Level 3 \| Internal \| Maximum \| Discounted cash flow \| Policyholders' account balances
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Lapse rate	42.00%	42.00%
Spread over LIBOR	1.59%	1.23%
Equity volatility curve	38.00%	25.00%
Level 3 \| Internal \| Maximum \| Discounted cash flow \| Corporate securities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate	25.00%	20.00%
Level 3 \| Internal \| Maximum \| Market comparables \| Corporate securities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
EBITDA multiples		6.7
Level 3 \| Internal \| Weighted Average \| Discounted cash flow \| Corporate securities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Discount rate	6.24%	8.66%
Level 3 \| Internal \| Weighted Average \| Market comparables \| Corporate securities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
EBITDA multiples		6.7
Level 3 \| Internal \| Fair Value, Measurements, Recurring \| Future policy benefits
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Future policy benefits	$ 21,325,619	$ 11,822,998
Level 3 \| Internal \| Fair Value, Measurements, Recurring \| Policyholders' account balances
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Policyholders’ account balances	303,060	196,892
Level 3 \| Internal \| Fair Value, Measurements, Recurring \| Corporate securities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Corporate securities	54,937	17,149
Level 3 \| Internal \| Fair Value, Measurements, Recurring \| Reinsurance recoverables
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Reinsurance recoverables	$ 488,335	$ 302,814

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Market valuation of entity divided by earnings before interest, taxes, depreciation, and amortization (EBITDA), used as an input to measure fair value.

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Fair Value Inputs Equity Volatility Curve

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Actuarially determined assumption around contract lapse rates used as in input in calculating fair value of future policy benefits (primarily embedded derivatives associated with living benefit features on annuity contracts.

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Actuarially determined assumption around client mortality rates used as in input in calculating fair value of future policy benefits (primarily embedded derivatives associated with living benefit features on annuity contracts.

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Fair Value Inputs, Policyholder Age

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Fair Value Inputs Spread Over Libor

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Actuarially determined assumption around utilization rates used as in input in calculating fair value of future policy benefits (primarily embedded derivatives associated with living benefit features on annuity contracts.

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Actuarially determined assumption around withdrawal rates used as in input in calculating fair value of future policy benefits (primarily embedded derivatives associated with living benefit features on annuity contracts.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The aggregate amount of policy reserves (provided for future obligations including unpaid claims and claims adjustment expenses) and policy benefits (liability for future policy benefits) as of the balance sheet date; grouped amount of all the liabilities associated with the company's insurance policies.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of investment in marketable security.

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Amount due to policyholders for funds held that are returnable under the terms of insurance contracts, classified as other.

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