Schedule II - Condensed Financial Information of Registrant (Statements of Income (Parent Company)) (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
Consolidated Financial Information of Registrant
Net investment gains (losses)									$ 210,465	$ 125,481	$ 56,581
Other income									2,564	1,764	1,522
Total revenues	1,608,601	1,420,501	1,415,747	1,378,705	1,370,953	1,279,731	1,270,949	1,234,351	5,823,554	5,155,984	4,724,069
Total operating costs and expenses									5,121,626	4,642,898	4,125,159
Interest expense									126,302	112,512	106,969
Income before income taxes									701,928	513,086	598,910
Federal income taxes:
Income tax expense									(191,285)	(121,945)	(152,226)
Net income	165,489	100,947	108,838	135,318	117,027	76,410	82,184	115,590	510,592	391,211	446,405
Parent Company [Member]
Consolidated Financial Information of Registrant
Management fees and investment income including dividends from subsidiaries of $502,327, $405,917 and $150,545 for the years ended December 31, 2011, 2010 and 2009, respectively									29,961	514,057	411,623
Net investment gains (losses)									71,130	45,962	(1,891)
Other income									271	96	158
Total revenues									101,362	560,115	409,890
Total operating costs and expenses									133,326	118,922	117,658
Interest expense									124,298	111,184	105,510
Income before income taxes									(156,262)	330,009	186,722
Federal income taxes:
Federal income taxes provided by subsidiaries on a separate return basis									132,379	79,200	28,377
Federal income tax expense on a consolidated return basis									(160,226)	(89,144)	(138,389)
Income tax expense									(27,847)	(9,944)	(110,012)
Income before undistributed equity in net income (loss) of subsidiaries									(184,109)	320,065	76,710
Equity in undistributed net income (loss) of subsidiaries									694,701	71,146	369,695
Net income									$ 510,592	$ 391,211	$ 446,405