Consolidated Statements Of Shareholders' Equity (USD $)		Share Capital [Member]	Additional Paid-In Capital [Member]	Treasury Shares [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2008		$ 1,471,000	$ 1,314,785,000		$ 105,632,000	$ 994,974,000	$ 2,416,862,000
Cumulative effect adjustment	[1]				(136,848,000)	136,848,000
Net income						606,887,000	606,887,000
Dividends						(36,689,000)	(36,689,000)
Other comprehensive income:
Net unrealized gains, net of deferred income tax					199,724,000		199,724,000
Portion of OTTI losses recognized in other comprehensive income, net of deferred income tax					(18,659,000)		(18,659,000)
Other comprehensive (loss) income					181,065,000		181,065,000
Stock compensation		21,000	45,149,000				45,170,000
Balance at Dec. 31, 2009		1,492,000	1,359,934,000		149,849,000	1,702,020,000	3,213,295,000
Cumulative effect adjustment	[2]				(41,889,000)	41,889,000
Net income						665,005,000	665,005,000
Dividends						(47,712,000)	(47,712,000)
Other comprehensive income:
Other comprehensive (loss) income					(50,825,000)		(50,825,000)
Stock compensation		38,000	40,697,000				40,735,000
Share repurchases				(674,662,000)			(674,662,000)
Shares cancelled			(561,851,000)	561,851,000
Recapitalization	[3]	598,525,000	(598,525,000)
Repurchase of founder warrants			(70,016,000)				(70,016,000)
Balance at Dec. 31, 2010		600,055,000	170,239,000	(112,811,000)	57,135,000	2,361,202,000	3,075,820,000
Net income						274,548,000	274,548,000
Dividends - partial par value reduction		(42,902,000)					(42,902,000)
Other comprehensive income:
Other comprehensive (loss) income					(42,651,000)		(42,651,000)
Stock compensation			(38,394,000)	62,921,000			24,527,000
Share repurchases				(86,700,000)			(86,700,000)
Repurchase of founder warrants			(53,620,000)				(53,620,000)
Balance at Dec. 31, 2011		$ 557,153,000	$ 78,225,000	$ (136,590,000)	$ 14,484,000	$ 2,635,750,000	$ 3,149,022,000

[1] Cumulative effect adjustment reflects adoption of ASC 320-10-65 as of April 1, 2009.

[2] Cumulative effect adjustment reflects adoption of ASU 2010-11 as of July 1, 2010.

[3] (3) As a result of the redomestication, share capital was increased on a net basis by $598,525. For additional details refer to Note 11.