Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Operating Activities
Net income (loss)	$ 1,811	$ 2,389
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net realized (gains) losses	(231)	(196)
Equity in net (income) or loss of investments accounted for using the equity method and other income or loss	(107)	(174)
Amortization of intangible assets	97	48
Share-based compensation	99	84
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	1,386	1,369
Unearned premiums, net of ceded unearned premiums	338	879
Premiums receivable	(1,294)	(1,682)
Deferred acquisition costs	19	(80)
Reinsurance balances payable	663	616
Deferred income tax assets, net	109	45
Other items, net	(308)	(216)
Net cash provided by operating activities	2,582	3,082
Investing Activities
Purchases of fixed maturity investments	(17,568)	(14,123)
Purchases of equity securities	(987)	(654)
Purchases of other investments	(1,232)	(1,369)
Proceeds from sales of fixed maturity investments	13,823	11,220
Proceeds from sales of equity securities	1,043	547
Proceeds from sales, redemptions and maturities of other investments	1,091	619
Proceeds from redemptions and maturities of fixed maturity investments	1,326	878
Net settlements of derivative instruments	240	12
Net (purchases) sales of short-term investments	52	(25)
Purchases of fixed assets	(21)	(26)
Other	(3)	3
Net cash used for investing activities	(2,236)	(2,918)
Financing Activities
Purchases of common shares under share repurchase program	(359)	0
Proceeds from common shares issued, net	19	(8)
Common dividends paid	(7)	0
Preferred dividends paid	(20)	(20)
Other	(2)	0
Net cash used for financing activities	(369)	(28)
Effects of exchange rate changes on foreign currency cash and restricted cash	71	(7)
Increase (decrease) in cash and restricted cash	48	129
Cash and restricted cash, beginning of year	1,760	1,498
Cash and restricted cash, end of period	1,808	1,627
Income taxes paid (received)	149	145
Interest paid	$ 64	$ 63