Recent Accounting Pronouncements Recent Accounting Pronouncements (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	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	377,600,000			364,937,000
Stockholders equity	4,126,916,000			3,953,356,000
Other operating expenses	431,779,000	386,129,000
Income before income taxes	187,303,000	159,194,000
Federal and foreign income taxes	(52,071,000)	(43,599,000)
Net Income (Loss)	135,318,000	115,590,000
Earnings Per Share, Basic	$ 0.98	$ 0.82
Earnings Per Share, Diluted	$ 0.94	$ 0.78
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		384,831,000
Income before income taxes		160,492,000
Federal and foreign income taxes		(44,000,000)
Net Income (Loss)		116,487,000
Earnings Per Share, Basic		$ 0.83
Earnings Per Share, Diluted		$ 0.79
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		386,129,000
Income before income taxes		159,194,000
Federal and foreign income taxes		(43,599,000)
Net Income (Loss)		$ 115,590,000
Earnings Per Share, Basic		$ 0.82
Earnings Per Share, Diluted		$ 0.78