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			(83)	(8,343)
Change in redeemable noncontrolling interests				(261)
Exercise of options and issuance of restricted stock awards			219	4,704
Change in net unrealized gains on investments	$ 423				(423)
Net income	304,096					304,096
Net income attributable to redeemable noncontrolling interests	(51,829)					(51,829)
Dividends on common shares						(27,479)
Dividends on preference shares	(11,191)					(11,191)
End of period at Jun. 30, 2015		400,000	46,013	750,484	2,993	3,637,454
Total shareholders’ equity	4,836,944
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			(2,420)	(269,847)
Change in redeemable noncontrolling interests				(731)
Exercise of options and issuance of restricted stock awards			215	5,465
Change in net unrealized gains on investments	(229)				229
Net income	350,737					350,737
Net income attributable to redeemable noncontrolling interests	(75,226)					(75,226)
Dividends on common shares						(26,198)
Dividends on preference shares	(11,191)					(11,191)
End of period at Jun. 30, 2016	4,703,217	$ 400,000	$ 41,496	$ 242,561	$ 2,337	$ 4,016,823
Total shareholders’ equity	$ 4,703,217