Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
QuarterlyFinancialDataAbstract
Total revenues	$ 286,154	$ 250,028	$ 283,524	$ 290,576	$ 310,807	$ 280,135	$ 375,418	$ 313,201	$ 1,110,282	$ 1,279,561	$ 1,522,878
Total benefits and expenses	72,431	(332,523)	96,720	93,190	55,114	(131,867)	716,619	(217,998)	(70,182)	421,868	1,840,496
Income Loss From Continuing Operations Before Income Taxes And Operating Joint Ventures	213,723	582,551	186,804	197,386	255,693	412,002	(341,201)	531,199	1,180,464	857,693	(317,618)
Net income	$ 156,738	$ 400,296	$ 143,670	$ 147,388	$ 189,112	$ 309,747	$ (237,147)	$ 372,347	$ 848,092	$ 634,059	$ (151,555)