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	$ 681,086	$ 540,685	$ 2,027,733	$ 1,599,962
Total benefits and expenses	(178,013)	181,818	287,332	1,095,178
Income Loss From Continuing Operations Before Income Taxes And Operating Joint Ventures	859,099	358,867	1,740,401	504,784
Net income	$ 577,646	$ 315,599	$ 1,236,698	$ 423,540