Comprehensive Income (Loss) (Reclassification From Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net realized capital gains (losses)	$ 44,122	$ (112,904)	$ (296,869)	$ 89,664
Other underwriting expenses	1,978	2,285	7,150	5,736
Income tax expense (benefit)	(416)	(480)	(1,502)	(1,205)
Net income (loss)	1,563	1,806	5,649	4,532
URA(D) On Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other underwriting expenses	2,683	(3,343)	12,751	36,591
Income tax expense (benefit)	(524)	738	(2,660)	(7,767)
Net income (loss)	2,160	(2,605)	10,092	28,824
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)	2,683	(3,343)	12,751	36,591
Income tax expense (benefit)	(524)	738	(2,660)	(7,767)
Net income (loss)	2,160	(2,605)	10,092	28,824
Benefit Plan Net Gain (Loss) [Member] | Reclassification From Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other underwriting expenses	1,978	2,285	7,150	5,736
Income tax expense (benefit)	(416)	(480)	(1,502)	(1,205)
Net income (loss)	$ 1,563	$ 1,806	$ 5,649	$ 4,532