Comprehensive Income (Loss) (Reclassification From Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net gains (losses) on investments	$ (39,250)	$ 7,462	$ (48,767)	$ 18,986
Income tax expense (benefit)	24,516	(115,228)	34,745	(145,550)
NET INCOME (LOSS)	(85,683)	465,807	(84,631)	585,250
URA(D) On Securities [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net gains (losses) on investments	7,793	8,198	10,611	10,068
Income tax expense (benefit)	(1,622)	(1,757)	(2,185)	(2,136)
NET INCOME (LOSS)	6,171	6,442	8,426	7,932
Benefit Plan Net Gain (Loss) [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other underwriting expenses	(959)	(2,586)	(1,919)	(5,172)
Income tax expense (benefit)	(202)	(543)	(404)	(1,086)
NET INCOME (LOSS)	$ 758	$ 2,043	$ 1,515	$ 4,086