Shareholders' Equity (Roll Forward of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,281,768	$ 1,321,316	$ 1,428,387	$ 1,349,210
OCI, before reclassifications, net of tax	(110,522)	15,926	(251,330)	(14,489)
Amounts reclassified from AOCI, net of tax	900	(4,376)	858	(7,666)
Net OCI, current period	(109,622)	11,550	(250,472)	(22,155)
Ending balance	1,169,889	1,424,040	1,169,889	1,424,040
Unrealized Investment Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(125,907)	41,626	14,929	75,388
OCI, before reclassifications, net of tax	(110,191)	15,918	(250,999)	(14,497)
Amounts reclassified from AOCI, net of tax	1,053	(4,376)	1,025	(7,723)
Net OCI, current period	(109,138)	11,542	(249,974)	(22,220)
Ending balance	(235,045)	53,168	(235,045)	53,168
Non-credit Impairments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0	0	0	(57)
OCI, before reclassifications, net of tax	(331)	0	(331)	0
Amounts reclassified from AOCI, net of tax	0	0	0	57
Net OCI, current period	(331)	0	(331)	57
Ending balance	(331)	0	(331)	0
Unrecognized Change in Defined Benefit and Post Retirement Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1,341	(104)	1,355	(104)
OCI, before reclassifications, net of tax	0	8	0	8
Amounts reclassified from AOCI, net of tax	(153)	0	(167)	0
Net OCI, current period	(153)	8	(167)	8
Ending balance	1,188	(96)	1,188	(96)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(124,566)	41,522	16,284	75,227
Ending balance	$ (234,188)	$ 53,072	$ (234,188)	$ 53,072