Fair Value of Financial Instruments - Carrying and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	$ 193	$ 194
Policyholder account balances – certain investment contracts	(135,683)	(136,245)
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt	(397)	(399)
Long-term debt	(5,466)	(5,605)
Fair Value | Mortgage loans on real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	22,057	21,756
Fair Value | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	7,351	6,721
Fair Value | Policy loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	2,606	2,626
Fair Value | Policyholder account balances – certain investment contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	(35,870)	(36,710)
Fair Value | Policyholder account balances – funding agreements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	(4,364)	(3,778)
Fair Value | Funds withheld reinsurance-related liabilities – excluding embedded derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Funds withheld reinsurance-related liabilities – excluding embedded derivatives	(17,472)	(17,633)
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt	(400)	(400)
Long-term debt	(5,969)	(5,866)
Carrying Amount | Mortgage loans on real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	22,627	22,273
Carrying Amount | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	7,351	6,721
Carrying Amount | Policy loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	2,606	2,626
Carrying Amount | Policyholder account balances – certain investment contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	(44,028)	(43,793)
Carrying Amount | Policyholder account balances – funding agreements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	(4,399)	(3,749)
Carrying Amount | Funds withheld reinsurance-related liabilities – excluding embedded derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Funds withheld reinsurance-related liabilities – excluding embedded derivatives	(17,472)	(17,633)
(Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	0	0
(Level 1) | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt	0	0
Long-term debt	0	0
(Level 1) | Fair Value | Mortgage loans on real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	0	0
(Level 1) | Fair Value | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	0	0
(Level 1) | Fair Value | Policy loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	0	0
(Level 1) | Fair Value | Policyholder account balances – certain investment contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	0	0
(Level 1) | Fair Value | Policyholder account balances – funding agreements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	0	0
(Level 1) | Fair Value | Funds withheld reinsurance-related liabilities – excluding embedded derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Funds withheld reinsurance-related liabilities – excluding embedded derivatives	0	0
(Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	165	193
(Level 2) | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt	(397)	(399)
Long-term debt	(5,466)	(5,605)
(Level 2) | Fair Value | Mortgage loans on real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	0	0
(Level 2) | Fair Value | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	1,090	962
(Level 2) | Fair Value | Policy loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	2,606	2,626
(Level 2) | Fair Value | Policyholder account balances – certain investment contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	0	0
(Level 2) | Fair Value | Policyholder account balances – funding agreements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	(4,364)	(3,778)
(Level 2) | Fair Value | Funds withheld reinsurance-related liabilities – excluding embedded derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Funds withheld reinsurance-related liabilities – excluding embedded derivatives	0	0
(Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	28	1
(Level 3) | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt	0	0
Long-term debt	0	0
(Level 3) | Fair Value | Mortgage loans on real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	22,057	21,756
(Level 3) | Fair Value | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	6,261	5,759
(Level 3) | Fair Value | Policy loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other investments – short-term investments	0	0
(Level 3) | Fair Value | Policyholder account balances – certain investment contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	(35,870)	(36,710)
(Level 3) | Fair Value | Policyholder account balances – funding agreements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Policyholder account balances – certain investment contracts	0	0
(Level 3) | Fair Value | Funds withheld reinsurance-related liabilities – excluding embedded derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Funds withheld reinsurance-related liabilities – excluding embedded derivatives	$ (17,472)	$ (17,633)