Other Comprehensive Income (Loss) (Reclassification From Accumulated Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net realized capital gains (losses)	$ (160)	$ 208,426	$ 121,103	$ 533,758
Other underwriting expenses	(50,623)	(48,945)	(137,032)	(136,751)
Income tax expense (benefit)	(21,720)	(125,426)	(145,498)	(308,347)
NET INCOME (LOSS)	100,141	243,753	344,781	614,666
URA(D) On Securities [Member] | Reclassification From Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net realized capital gains (losses)	(1,070)	(1,729)	2,054	(4,062)
Income tax expense (benefit)	374	606	(595)	1,422
NET INCOME (LOSS)	(696)	(1,124)	1,459	(2,640)
Benefit Plan Liability [Member] | Reclassification From Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other underwriting expenses	1,269	2,262	3,640	6,402
Income tax expense (benefit)	(444)	(792)	(1,274)	(2,241)
NET INCOME (LOSS)	$ 825	$ 1,470	$ 2,366	$ 4,161