Fair Values of Financial Instruments (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) limitedPartnershipFund entity	Dec. 31, 2022 USD ($) limitedPartnershipFund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Coinsurance deposits	$ 14,582,728	$ 13,254,956	[1]
Fixed Index Annuities - Embedded Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Coinsurance deposits	$ 1,182,600	$ 1,173,400
Limited partnership funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Limited partnerships and limited liability companies, number of consolidated limited partnership funds measured using NAV as practical expedient | limitedPartnershipFund	1	2
Limited partnerships and limited liability companies, number of consolidated limited partnership funds that terminated and liquidated during the period | limitedPartnershipFund	1
Unfunded commitments	$ 180,900	$ 926,300
Significant Unobservable Inputs (Level 3) | Real estate investments | Fair Value, Measurements, Recurring | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash flow modeling period	10 years
Significant Unobservable Inputs (Level 3) | Limited partnerships and limited liability companies | Fair Value, Measurements, Recurring | Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Variable interest entities, number of consolidated variable interest entities | entity	2
Discount Rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, sensitivity, discount rate adjustment (basis points)	0.0100
Fixed index annuities embedded derivative, adjustment due to change in discount rate	$ (364,700)
Discount Rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, sensitivity, discount rate adjustment (basis points)	0.0100
Fixed index annuities embedded derivative, adjustment due to change in discount rate	$ 419,700

[1] Certain prior period amounts have been recast. See Note 1 - Significant Accounting Policies for more information.