Consolidated Balance Sheets (Parentheticals) (Unaudited) $ in Millions	Mar. 31, 2025 USD ($) shares	Dec. 31, 2024 USD ($) shares
Statement of Financial Position [Abstract]
Short-term investments, amortized cost	$ 4,434	$ 5,143
Fixed maturities available-for-sale, valuation allowance	63	70
Fixed maturities available-for-sale, amortized cost	114,930	115,083
Private debt held-to-maturity, valuation allowance	3	4
Restricted cash	278	261
Insurance and reinsurance balances receivable, valuation allowance	58	59
Valuation allowance for uncollectible reinsurance	$ 320	$ 310
Common Shares, shares issued | shares	412,107,421	419,625,986
Common Shares, shares outstanding | shares	400,748,485	400,703,663
Treasury Stock, Common, Shares | shares	11,358,936	18,922,323
Short-term investments	$ 4,432	$ 5,142
Equity securities	9,556	9,151
Private equities	15,506	14,769
Other investments	9,224	8,597
Cash, including restricted cash	2,250	2,549
Other assets	8,704	7,503
Repurchase agreements	3,124	2,731
Noncontrolling interests	5,029	4,373
Variable Interest Entity, Primary Beneficiary
Short-term investments	131	57
Equity securities	1,631	1,289
Private equities	22	22
Other investments	5,002	4,538
Cash, including restricted cash	205	114
Other assets	32	26
Repurchase agreements	1,102	815
Other liabilities	93	183
Noncontrolling interests	$ 4,117	$ 3,459