Derivative Instruments (Changes in Estimated Fair Value Related to Embedded Derivatives) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Changes In Estimated Fair Value Related To Embedded Derivatives [Line Items]
Total investment related gains (losses), net	$ 118,527	$ 48,243	$ 203,098	$ 142,614
Total benefits and expenses	2,532,485	2,665,400	4,990,218	4,987,675
Net income (loss)	198,296	(49,612)	334,960	135,923
Embedded Derivatives In Modified Coinsurance Or Funds Withheld Arrangements
Changes In Estimated Fair Value Related To Embedded Derivatives [Line Items]
Total investment related gains (losses), net	78,835	47,717	156,076	137,974
Net income (loss)	17,962	13,911	36,042	35,535
Embedded Derivatives In Equity Indexed Annuities [Member]
Changes In Estimated Fair Value Related To Embedded Derivatives [Line Items]
Total benefits and expenses	(27,285)	(28,019)	(51,125)	(61,015)
Net income (loss)	(15,600)	(30,845)	(33,976)	(60,395)
Embedded Derivatives In Variable Annuity Contracts [Member]
Changes In Estimated Fair Value Related To Embedded Derivatives [Line Items]
Total investment related gains (losses), net	(5,183)	35,809	(28,844)	87,123
Net income (loss)	$ (6,486)	$ 29,082	$ (20,154)	$ 41,274