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	$ 668,041	$ 681,086	$ 656,314	$ 690,333	$ 624,315	$ 540,685	$ 561,203	$ 498,074	$ 2,695,774	$ 2,224,277	$ 2,131,684
Total benefits and expenses	303,812	(178,013)	229,901	235,444	263,722	181,818	1,054,097	(140,737)	591,144	1,358,900	2,485,883
Income Loss From Continuing Operations Before Income Taxes And Operating Joint Ventures	364,229	859,099	426,413	454,889	360,593	358,867	(492,894)	638,811	2,104,630	865,377	(354,199)
Net income	$ 301,512	$ 577,646	$ 311,997	$ 347,055	$ 260,797	$ 315,599	$ (353,363)	$ 461,304	$ 1,538,210	$ 684,337	$ (132,743)