Consolidated Balance Sheets (Parentheticals) (Unaudited) $ in Millions	Sep. 30, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares
Statement of Financial Position [Abstract]
Short-term investments amortized cost	$ 5,455	$ 4,962
Fixed maturities, available-for-sale, valuation allowance	158	169
Fixed maturities, available-for-sale, at amortized cost	109,355	93,355
Fixed maturities, held-to-maturity, valuation allowance	0	34
Fixed maturities, held-to-maturity, fair value	0	8,439
Restricted cash	192	115
Premium Receivable, Allowance for Credit Loss	53	52
Valuation allowance for uncollectible reinsurance	$ 370	$ 351
Common Shares, shares issued | shares	431,451,586	446,376,614
Common Shares, shares outstanding | shares	407,984,339	414,594,856
Treasury Stock, Common, Shares | shares	23,467,247	31,781,758