Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Activities
Net income	$ 1,482,423	$ 2,239,462	$ 1,465,711
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized (gains) losses	651,568	(427,367)	(844,625)
Equity in net (income) or loss of investments accounted for using the equity method and other income or loss	153,157	(464,050)	(47,951)
Amortization of intangible assets	106,200	82,955	69,031
Share-based compensation	87,628	87,094	71,262
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	1,889,015	1,762,190	2,113,827
Unearned premiums, net of ceded unearned premiums	1,399,112	936,039	445,781
Premiums receivable	(1,109,229)	(685,214)	(318,643)
Deferred acquisition costs	(374,067)	(263,243)	(143,948)
Reinsurance balances payable	(35,509)	500,065	65,950
Other items, net	(435,071)	(340,376)	10,110
Net cash provided by operating activities	3,815,227	3,427,555	2,886,505
Investing Activities:
Purchases of fixed maturity investments	(16,390,475)	(35,451,858)	(39,765,277)
Purchases of equity securities	(796,998)	(1,175,480)	(1,595,010)
Purchases of other investments	(1,720,457)	(1,859,096)	(1,808,727)
Proceeds from sales of fixed maturity investments	11,844,004	33,577,445	37,949,346
Proceeds from sales of equity securities	1,554,116	918,145	1,147,264
Proceeds from sales, redemptions and maturities of other investments	1,221,072	1,765,533	1,029,578
Proceeds from redemptions and maturities of fixed maturity investments	714,519	1,628,755	871,134
Net settlements of derivative instruments	(68,818)	(40,072)	179,006
Net (purchases) sales of short-term investments	467,249	165,272	(1,029,681)
Change in cash collateral related to securities lending	0	0	81,210
Purchase of operating affiliate	0	(753,916)	0
Impact of the deconsolidation of the variable interest entity	0	(349,202)	0
Purchases of fixed assets	(51,672)	(41,394)	(39,872)
Other	125,405	(523,864)	(62,197)
Net cash used for investing activities	(3,102,055)	(2,139,732)	(3,043,226)
Financing Activities:
Proceeds from issuance of preferred shares, net	0	485,821	0
Redemption of preferred shares	0	(450,000)	0
Purchases of common shares under share repurchase program	(585,823)	(1,234,294)	(83,472)
Proceeds from common shares issued, net	6,660	6,418	1,876
Proceeds from borrowings	0	0	1,018,793
Repayments of borrowings	0	0	(359,000)
Change in cash collateral related to securities lending	0	0	(81,210)
Third party investment in non-redeemable noncontrolling interests	0	15,971	(2,867)
Dividends paid to redeemable noncontrolling interests	0	(1,907)	(4,945)
Other	(85,827)	(3,278)	73,715
Preferred dividends paid	(40,736)	(48,280)	(41,612)
Net Cash Provided by (Used in) Financing Activities	(705,726)	(1,229,549)	521,278
Effects of exchange rate changes on foreign currency cash and restricted cash	(48,889)	(34,047)	22,289
Increase (decrease) in cash and restricted cash	(41,443)	24,227	386,846
Cash and restricted cash, beginning of year	1,314,771	1,290,544	903,698
Cash and restricted cash, end of year	1,273,328	1,314,771	1,290,544
Supplemental cash flow information
Income taxes paid (received)	254,922	286,810	202,940
Interest paid	$ 128,425	$ 139,301	$ 133,491