Recent Accounting Pronouncements Recent Accounting Pronouncements (Details) (USD $)	3 Months Ended			6 Months Ended	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Dec. 31, 2010	Dec. 31, 2011
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					$ 51,000,000
Deferred policy acquisition costs	386,783,000			386,783,000		364,937,000
Stockholders equity	4,207,784,000			4,207,784,000		3,953,356,000
Other operating expenses	448,758,000	403,658,000	789,787,000	880,537,000
Income before income taxes	148,439,000	109,028,000	268,222,000	335,742,000
Federal and foreign income taxes	(39,535,000)	(26,908,000)	(70,507,000)	(91,606,000)
Net Income (Loss)	108,838,000	82,184,000	197,774,000	244,156,000
Earnings Per Share, Basic	$ 0.79	$ 0.58	$ 1.4	$ 1.77
Earnings Per Share, Diluted	$ 0.76	$ 0.56	$ 1.34	$ 1.7
Scenario, Previously Reported [Member]
Deferred policy acquisition costs						448,795,000
Deferred tax liabilities						31,623,000
Stockholders equity						4,008,426,000
Other operating expenses	1,160,622,000			787,190,000
Income before income taxes	110,327,000			270,819,000
Federal and foreign income taxes	(27,309,000)			(71,309,000)
Net Income (Loss)	83,082,000			199,569,000
Earnings Per Share, Basic	$ 0.59			$ 1.41
Earnings Per Share, Diluted	$ 0.56			$ 1.35
Restatement Adjustment [Member]
Deferred policy acquisition costs						364,937,000
Deferred tax liabilities						2,835,000
Stockholders equity						3,953,356,000
Other operating expenses	1,161,921,000			789,787,000
Income before income taxes	109,028,000			268,222,000
Federal and foreign income taxes	(26,908,000)			(70,507,000)
Net Income (Loss)	$ 82,184,000			$ 197,774,000
Earnings Per Share, Basic	$ 0.58			$ 1.40
Earnings Per Share, Diluted	$ 0.56			$ 1.34