Investments (Components Of Realized Gains And Losses) (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
Gain (Loss) on Investments [Line Items]
Gross realized gains on sale of invested assets									$ 183,592	$ 154,941	$ 242,421
Gross realized losses on sale of invested assets									(51,702)	(62,169)	(26,621)
Net realized and unrealized losses on derivatives									(3,608)	(70,090)	(3,958)
Gain on sale of program administrator									0	0	1,860
Net realized investment gains (losses)	14,379	149,813	8,663	133,581	31,632	(130,809)	58,878	50,376	306,436	10,077	285,612
Proceeds from sale of available for sale securities									236,336	646,479	2,703,695
Debt Securities [Member]
Gain (Loss) on Investments [Line Items]
Mark to market changes: trading securities									106,328	(8,078)	42,172
Equity Securities And Other Invested Assets [Member]
Gain (Loss) on Investments [Line Items]
Mark to market changes: trading securities									$ 71,826	$ (4,527)	$ 29,738