Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	Total	Preference Shares	Common Shares	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings
Beginning of period at Dec. 31, 2014		$ 400,000	$ 38,442	$ 0	$ 3,416	$ 3,423,857
Issuance of shares			7,435	754,384
Repurchase of shares			(2,026)	(209,462)
Change in redeemable noncontrolling interests				(403)
Exercise of options and issuance of restricted stock awards			270	7,164
Change in net unrealized gains on investments	$ 1,156				(1,156)
Net income	416,373					416,373
Net income attributable to redeemable noncontrolling interests	(82,982)					(82,982)
Dividends on common shares						(40,883)
Dividends on preference shares	(16,786)					(16,786)
End of period at Sep. 30, 2015		400,000	44,121	551,683	2,260	3,699,579
Total shareholders’ equity	4,697,643
Beginning of period at Dec. 31, 2015	4,732,184	400,000	43,701	507,674	2,108	3,778,701
Issuance of shares			0	0
Repurchase of shares			(2,741)	(306,693)
Change in redeemable noncontrolling interests				(1,040)
Exercise of options and issuance of restricted stock awards			196	13,112
Change in net unrealized gains on investments	(513)				513
Net income	538,798					538,798
Net income attributable to redeemable noncontrolling interests	(110,867)					(110,867)
Dividends on common shares						(38,886)
Dividends on preference shares	(16,786)					(16,786)
End of period at Sep. 30, 2016	4,807,790	$ 400,000	$ 41,156	$ 213,053	$ 2,621	$ 4,150,960
Total shareholders’ equity	$ 4,807,790