Fair Value (Activity Under Level 3, Fair Value Measurements Using Significant Unobservable Inputs By Asset Type) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Market Value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	$ 1,495,500	$ 951,712	$ 1,330,224	$ 772,979
Total gains or (losses) (realized/unrealized) Included in earnings	(13,418)	(224)	(19,372)	(434)
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)	12,107	17,503	11,857	(1,736)
Purchases, issuances and settlements	31,545	58,665	203,025	256,847
Transfer in and/or (out) of Level 3		(3,818)		(3,818)
Ending balance	1,525,734	1,023,838	1,525,734	1,023,838
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	(22,194)		(22,194)	(539)
Market Value [Member] \| Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	704,542	713,081	701,492	617,588
Total gains or (losses) (realized/unrealized) Included in earnings	(13,761)	(248)	(15,550)	(462)
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)	4,582	(549)	7,418	(3,906)
Purchases, issuances and settlements	10,208	14,345	12,211	113,409
Transfer in and/or (out) of Level 3		(4,795)		(4,795)
Ending balance	705,571	721,834	705,571	721,834
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	(17,279)		(17,279)	(539)
Market Value [Member] \| Asset Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	785,360	238,631	623,033	153,641
Total gains or (losses) (realized/unrealized) Included in earnings	206	121	(3,962)	125
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)	7,610	18,092	4,475	2,210
Purchases, issuances and settlements	22,100	38,886	191,730	139,754
Transfer in and/or (out) of Level 3
Ending balance	815,276	295,730	815,276	295,730
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	(4,915)		(4,915)
Market Value [Member] \| Foreign Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	5,598		5,699	1,750
Total gains or (losses) (realized/unrealized) Included in earnings	137	(97)	140	(97)
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)	(85)	(40)	(36)	(40)
Purchases, issuances and settlements	(763)	5,434	(916)	3,684
Transfer in and/or (out) of Level 3		977		977
Ending balance	4,887	6,274	4,887	6,274
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date
Fair Value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities		4,703		5,826
Total gains or (losses) (realized/unrealized) Included in earnings		(272)		(1,395)
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)
Purchases, issuances and settlements
Transfer in and/or (out) of Level 3
Ending balance		4,431		4,431
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date
Fair Value [Member] \| Foreign Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities		4,703		5,826
Total gains or (losses) (realized/unrealized) Included in earnings		(272)		(1,395)
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)
Purchases, issuances and settlements
Transfer in and/or (out) of Level 3
Ending balance		4,431		4,431
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date

Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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-Publisher FASB
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Amount of purchases, (sales), issuances and (settlements) of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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