Fair Value (Activity Under Level 3, Fair Value Measurements Using Significant Unobservable Inputs By Asset Type) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Market Value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	$ 1,023,838	$ 544,971	$ 772,979	$ 435,959
Total gains or (losses) (realized/unrealized) Included in earnings	845	1,018	411	3,229
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)	4,162	(670)	2,426	1,774
Purchases, issuances and settlements	102,364	82,289	359,211	185,127
Transfers in and/or (out) of Level 3	3,326	3,176	(492)	4,695
Ending balance	1,134,535	630,784	1,134,535	630,784
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			(539)
Market Value [Member] \| Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	721,834	542,878	617,588	428,215
Total gains or (losses) (realized/unrealized) Included in earnings	362	1,018	(100)	3,348
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)	(992)	(1,314)	(4,898)	1,130
Purchases, issuances and settlements	(1,349)	42,289	112,060	150,659
Transfers in and/or (out) of Level 3	4,189	3,176	(606)	4,695
Ending balance	724,044	588,047	724,044	588,047
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			(539)
Market Value [Member] \| Asset Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	295,730		153,641
Total gains or (losses) (realized/unrealized) Included in earnings	457		582
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)	5,028	644	7,238	644
Purchases, issuances and settlements	103,574	40,000	243,328	40,000
Transfers in and/or (out) of Level 3
Ending balance	404,789	40,644	404,789	40,644
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
Market Value [Member] \| Foreign Corporate [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	6,274	2,093	1,750	7,744
Total gains or (losses) (realized/unrealized) Included in earnings	26		(71)	(119)
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)	126		86
Purchases, issuances and settlements	139		3,823	(5,532)
Transfers in and/or (out) of Level 3	(863)		114
Ending balance	5,702	2,093	5,702	2,093
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	4,431		5,826	2,337
Total gains or (losses) (realized/unrealized) Included in earnings	1,371		(24)	369
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)
Purchases, issuances and settlements	(2,054)		(2,054)	(2,706)
Transfers in and/or (out) of Level 3
Ending balance	3,748		3,748
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 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance fixed maturities	4,431		5,826	2,337
Total gains or (losses) (realized/unrealized) Included in earnings	1,371		(24)	369
Total gains or (losses) (realized/unrealized) Included in other comprehensive income (loss)
Purchases, issuances and settlements	(2,054)		(2,054)	(2,706)
Transfers in and/or (out) of Level 3
Ending balance	3,748		3,748
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
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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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