Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010
QuarterlyFinancialDataAbstract
Total revenues	$ 310,807	$ 280,135	$ 375,418	$ 313,201	$ 335,148	$ 413,949	$ 402,919	$ 370,862	$ 1,279,561	$ 1,522,878	[1]	$ 1,574,025	[1]
Total benefits and expenses	55,114	(131,867)	716,619	(217,998)	138,059	1,133,796	358,357	210,284	421,868	1,840,496	[1]	1,040,729	[1]
Income Loss From Continuing Operations Before Income Taxes And Operating Joint Ventures	255,693	412,002	(341,201)	531,199	197,089	(719,847)	44,562	160,578	857,693	(317,618)	[1]	533,296	[1]
Net income	$ 189,112	$ 309,747	$ (237,147)	$ 372,347	$ 132,003	$ (439,731)	$ 34,652	$ 121,521	$ 634,059	$ (151,555)	[1]	$ 413,790	[1]

[1] “As previously reported” column represents balances reported in the Annual Report on Form 10-K for the year ended December 31, 2011, originally filed with the SEC on March 9, 2012. “As currently reported” column was included in the 8-K filed with the SEC on November 28, 2012.