Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities
Net income	$ 4,442	$ 1,482	$ 2,239
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized (gains) losses	182	651	(427)
Equity in net (income) or loss of investments accounted for using the equity method and other income or loss	(215)	154	(464)
Amortization of intangible assets	95	106	82
Share-based compensation	93	88	88
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	2,138	1,890	1,762
Unearned premiums, net of ceded unearned premiums	1,028	1,399	935
Premiums receivable	(981)	(1,110)	(685)
Deferred acquisition costs	(235)	(374)	(263)
Reinsurance balances payable	455	(36)	499
Deferred income tax assets, net	(1,161)	(121)	(167)
Other items, net	(92)	(313)	(174)
Net cash provided by operating activities	5,749	3,816	3,425
Investing Activities:
Purchases of fixed maturity investments	(18,062)	(16,390)	(35,452)
Purchases of equity securities	(456)	(797)	(1,175)
Purchases of other investments	(2,171)	(1,720)	(1,859)
Proceeds from sales of fixed maturity investments	14,105	11,844	33,577
Proceeds from sales of equity securities	288	1,554	918
Proceeds from sales, redemptions and maturities of other investments	768	1,220	1,766
Proceeds from redemptions and maturities of fixed maturity investments	781	715	1,629
Net settlements of derivative instruments	50	(69)	(39)
Net (purchases) sales of short-term investments	(696)	467	165
Purchase of operating affiliate	0	0	(754)
Impact of the deconsolidation of the variable interest entity	0	0	(349)
Purchases of fixed assets	(52)	(50)	(41)
Other	(23)	125	(524)
Net cash used for investing activities	(5,468)	(3,101)	(2,138)
Financing Activities:
Proceeds from issuance of preferred shares, net	0	0	486
Redemption of preferred shares	0	0	(450)
Purchases of common shares under share repurchase program	0	(586)	(1,234)
Proceeds from common shares issued, net	(2)	6	6
Third party investment in non-redeemable noncontrolling interests	0	0	16
Third party investment in redeemable noncontrolling interests	(22)	0	0
Dividends paid to redeemable noncontrolling interests	0	0	(2)
Other	(5)	(86)	(4)
Preferred dividends paid	(40)	(40)	(47)
Net Cash Provided by (Used in) Financing Activities	(69)	(706)	(1,229)
Effects of exchange rate changes on foreign currency cash and restricted cash	13	(50)	(34)
Increase (decrease) in cash and restricted cash	225	(41)	24
Cash and restricted cash, beginning of year	1,273	1,314	1,290
Cash and restricted cash, end of year	1,498	1,273	1,314
Supplemental cash flow information
Income taxes paid (received)	267	255	286
Interest paid	$ 127	$ 128	$ 139