Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Preference shares	Common shares	Additional paid-in capital	Accumulated other comprehensive income (loss)	Retained earnings
Beginning balance at Dec. 31, 2021		$ 750,000	$ 44,445	$ 608,121	$ (10,909)	$ 5,232,624
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of shares			(875)	(136,656)
Issuance of restricted stock awards			311	11,609
Change in redeemable noncontrolling interests				(3,989)
Change in net unrealized gains (loss) on investments, net of tax	$ (2,417)				(2,417)
Foreign currency translation adjustments, net of tax	(1,842)				(1,842)
Net income (loss)	(664,219)
Net (income) loss attributable to redeemable noncontrolling interests	(37,419)					(37,419)
Dividends on common shares	(32,400)					(32,437)
Dividends on preference shares	(17,688)					(17,688)
Ending balance at Jun. 30, 2022	5,738,659	750,000	43,881	479,085	(15,168)	4,480,861
Beginning balance at Mar. 31, 2022		750,000	44,193	513,631	(12,834)	4,821,970
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of shares			(298)	(43,799)
Issuance of restricted stock awards			(14)	12,379
Change in redeemable noncontrolling interests				(3,126)
Change in net unrealized gains (loss) on investments, net of tax	(3,251)				(3,251)
Foreign currency translation adjustments, net of tax	917				917
Net income (loss)	(266,738)
Net (income) loss attributable to redeemable noncontrolling interests	(49,331)					(49,331)
Dividends on common shares						(16,196)
Dividends on preference shares	(8,844)					(8,844)
Ending balance at Jun. 30, 2022	5,738,659	750,000	43,881	479,085	(15,168)	4,480,861
Beginning balance at Dec. 31, 2022	5,325,274	750,000	43,718	475,647	(15,462)	4,071,371
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares			7,245	1,344,326
Issuance of restricted stock awards			219	7,024
Change in redeemable noncontrolling interests				(1,782)
Change in net unrealized gains (loss) on investments, net of tax	1,308				1,308
Foreign currency translation adjustments, net of tax	104				104
Net income (loss)	1,215,066
Net (income) loss attributable to redeemable noncontrolling interests	(442,291)					(442,291)
Dividends on common shares	(36,000)					(35,992)
Dividends on preference shares	(17,688)					(17,688)
Ending balance at Jun. 30, 2023	7,402,813	750,000	51,182	1,825,215	(14,050)	4,790,466
Beginning balance at Mar. 31, 2023		750,000	43,932	467,623	(14,838)	4,618,818
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares			7,245	1,344,326
Issuance of restricted stock awards			5	13,942
Change in redeemable noncontrolling interests				(676)
Change in net unrealized gains (loss) on investments, net of tax	390				390
Foreign currency translation adjustments, net of tax	398				398
Net income (loss)	374,776
Net (income) loss attributable to redeemable noncontrolling interests	(174,907)					(174,907)
Dividends on common shares						(19,377)
Dividends on preference shares	(8,844)					(8,844)
Ending balance at Jun. 30, 2023	$ 7,402,813	$ 750,000	$ 51,182	$ 1,825,215	$ (14,050)	$ 4,790,466