Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
QuarterlyFinancialDataAbstract
Total revenues	$ 250,028	$ 280,135	$ 824,127	$ 968,754
Total benefits and expenses	(332,523)	(131,867)	(142,614)	366,754
Income Loss From Continuing Operations Before Income Taxes And Operating Joint Ventures	582,551	412,002	966,741	602,000
Net income	$ 400,296	$ 309,747	$ 691,354	$ 444,947