Consolidated Balance Sheets (Parentheticals) (Unaudited) $ in Millions	Mar. 31, 2024 USD ($) shares	Dec. 31, 2023 USD ($) shares
Statement of Financial Position [Abstract]
Short-term investments amortized cost	$ 5,108	$ 4,551
Fixed maturities, available-for-sale, valuation allowance	115	156
Fixed maturities, available-for-sale, at amortized cost	113,479	111,128
Private debt held-to-maturity, amortized cost	5	4
Restricted cash	143	172
Premium Receivable, Allowance for Credit Loss	47	53
Valuation allowance for uncollectible reinsurance	$ 375	$ 367
Common Shares, shares issued | shares	431,451,586	431,451,586
Common Shares, shares outstanding | shares	406,033,066	405,269,637
Treasury Stock, Common, Shares | shares	25,418,520	26,181,949
Short-term investments	$ 5,107	$ 4,551
Equity securities	3,769	3,455
Private equities	14,281	14,078
Other Investments	6,216	5,527
Cash, including restricted cash	2,651	2,621
Other Assets	7,251	7,508
Repurchase agreements	3,022	2,833
Noncontrolling interests	3,896	4,184
Variable Interest Entity, Primary Beneficiary
Short-term investments	65	217
Equity securities	1,163	1,078
Private equities	22	21
Other Investments	4,408	3,773
Cash, including restricted cash	127	117
Other Assets	14	33
Other liabilities	68	18
Repurchase agreements	1,229	1,009
Noncontrolling interests	$ 2,943	$ 2,705