Fair Values of Financial Instruments - Schedule of Fair Value, Valuation Techniques and Significant Unobservable Inputs for Financial Instruments Categorized as Level 3 (Details) $ in Thousands	Dec. 31, 2022 USD ($) yr	Dec. 31, 2021 USD ($) yr
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Debt securities, available-for-sale	$ 7,611,633	$ 9,068,946
Derivatives, index options	23,669	101,622
Level 3
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Debt securities, available-for-sale	462,796	326,962
Derivatives, index options	23,669	101,622
Mortgage loans	457,873	513,246
Total assets	119,006	223,359
Total liabilities	82,800	150,630
Level 3 | Discounted cash flow
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Debt securities, available-for-sale	76,003	113,268
Mortgage loans	19,334	8,469
Level 3 | Broker prices
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivatives, index options	23,669	101,622
Level 3 | Deterministic cash flow model
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Policyholder account balances	62,258	142,761
Level 3 | Black-Scholes model
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Share based compensation	$ 20,542	$ 7,869
Discount rate | Level 3 | Discounted cash flow | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Debt Securities, available-for-sale, measurement input	0.0432	0.0240
Discount rate | Level 3 | Discounted cash flow | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Debt Securities, available-for-sale, measurement input	0.0728	0.0614
Discount rate | Level 3 | Discounted cash flow | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Debt Securities, available-for-sale, measurement input	0.0579	0.0406
Implied volatility | Level 3 | Broker prices | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivatives, index options, measurement input	0.1294	0.1176
Implied volatility | Level 3 | Broker prices | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivatives, index options, measurement input	0.3475	0.1654
Implied volatility | Level 3 | Broker prices | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivatives, index options, measurement input	0.1932	0.1455
Spread | Level 3 | Discounted cash flow | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Mortgage loans, measurement input	0.0150	0.0100
Spread | Level 3 | Discounted cash flow | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Mortgage loans, measurement input	0.0300	0.0250
Projected option cost | Level 3 | Deterministic cash flow model | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Policyholder account balances, measurement input	0.0000	0.0003
Projected option cost | Level 3 | Deterministic cash flow model | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Policyholder account balances, measurement input	0.0607	0.1449
Projected option cost | Level 3 | Deterministic cash flow model | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Policyholder account balances, measurement input	0.0065	0.0265
Expected term | Level 3 | Black-Scholes model | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Share based compensation, measurement input | yr	0.9	1.9
Expected term | Level 3 | Black-Scholes model | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Share based compensation, measurement input | yr	10	10
Expected volatility | Level 3 | Black-Scholes model
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Share based compensation, measurement input	0.3618	0.3505