Consolidated Balance Sheets (Parentheticals) (Unaudited) $ in Millions	Jun. 30, 2025 USD ($) shares	Dec. 31, 2024 USD ($) shares
Statement of Financial Position [Abstract]
Short-term investments, amortized cost	$ 4,508	$ 5,143
Fixed maturities available-for-sale, valuation allowance	71	70
Fixed maturities available-for-sale, amortized cost	118,947	115,083
Private debt held-to-maturity, valuation allowance	3	4
Restricted cash	182	261
Insurance and reinsurance balances receivable, valuation allowance	55	59
Valuation allowance for uncollectible reinsurance	$ 323	$ 310
Common Shares, shares issued | shares	412,107,421	419,625,986
Common Shares, shares outstanding | shares	398,660,788	400,703,663
Treasury Stock, Common, Shares | shares	13,446,633	18,922,323
Short-term investments	$ 4,508	$ 5,142
Equity securities	9,913	9,151
Private equities	16,313	14,769
Other investments	9,032	8,597
Cash, including restricted cash	2,371	2,549
Other assets	9,290	7,503
Repurchase agreements	3,059	2,731
Noncontrolling interests	5,052	4,373
Variable Interest Entity, Primary Beneficiary
Short-term investments	155	57
Equity securities	1,906	1,289
Private equities	22	22
Other investments	4,441	4,538
Cash, including restricted cash	189	114
Other assets	78	26
Repurchase agreements	700	815
Other liabilities	77	183
Noncontrolling interests	$ 4,238	$ 3,459