Summary of Investments - Fair Value of Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fixed maturities:
Carrying Value	$ 1,651,468	$ 1,719,790
Fixed maturities
Fixed maturities:
Cost or Amortized Cost	1,671,758	1,656,797
Gross Unrealized Appreciation	18,056	71,642
Gross Unrealized Depreciation	38,346	8,649
Fair Value	1,651,468	1,719,790
Allowance for Credit Losses	0	0
Carrying Value	1,651,468	1,719,790
U.S. Treasury
Fixed maturities:
Cost or Amortized Cost	42,292	42,425
Gross Unrealized Appreciation	6	216
Gross Unrealized Depreciation	1,900	718
Fair Value	40,398	41,923
Allowance for Credit Losses	0	0
Carrying Value	40,398	41,923
U.S. government agency
Fixed maturities:
Cost or Amortized Cost	73,017	60,074
Gross Unrealized Appreciation	632	2,155
Gross Unrealized Depreciation	2,691	562
Fair Value	70,958	61,667
Allowance for Credit Losses	0	0
Carrying Value	70,958	61,667
States, municipalities and political subdivisions \| General obligations \| Midwest
Fixed maturities:
Cost or Amortized Cost	70,491	71,863
Gross Unrealized Appreciation	745	2,483
Gross Unrealized Depreciation	42	0
Fair Value	71,194	74,346
Allowance for Credit Losses	0	0
Carrying Value	71,194	74,346
States, municipalities and political subdivisions \| General obligations \| Northeast
Fixed maturities:
Cost or Amortized Cost	22,020	22,061
Gross Unrealized Appreciation	179	701
Gross Unrealized Depreciation	15	0
Fair Value	22,184	22,762
Allowance for Credit Losses	0	0
Carrying Value	22,184	22,762
States, municipalities and political subdivisions \| General obligations \| South
Fixed maturities:
Cost or Amortized Cost	68,387	90,171
Gross Unrealized Appreciation	638	3,873
Gross Unrealized Depreciation	11	0
Fair Value	69,014	94,044
Allowance for Credit Losses	0	0
Carrying Value	69,014	94,044
States, municipalities and political subdivisions \| General obligations \| West
Fixed maturities:
Cost or Amortized Cost	93,789	93,968
Gross Unrealized Appreciation	1,262	5,110
Gross Unrealized Depreciation	14	0
Fair Value	95,037	99,078
Allowance for Credit Losses	0	0
Carrying Value	95,037	99,078
States, municipalities and political subdivisions \| Special revenue \| Midwest
Fixed maturities:
Cost or Amortized Cost	112,262	114,997
Gross Unrealized Appreciation	2,305	7,292
Gross Unrealized Depreciation	26	0
Fair Value	114,541	122,289
Allowance for Credit Losses	0	0
Carrying Value	114,541	122,289
States, municipalities and political subdivisions \| Special revenue \| Northeast
Fixed maturities:
Cost or Amortized Cost	55,684	55,811
Gross Unrealized Appreciation	769	3,921
Gross Unrealized Depreciation	142	0
Fair Value	56,311	59,732
Allowance for Credit Losses	0	0
Carrying Value	56,311	59,732
States, municipalities and political subdivisions \| Special revenue \| South
Fixed maturities:
Cost or Amortized Cost	198,958	201,383
Gross Unrealized Appreciation	3,820	14,365
Gross Unrealized Depreciation	365	78
Fair Value	202,413	215,670
Allowance for Credit Losses	0	0
Carrying Value	202,413	215,670
States, municipalities and political subdivisions \| Special revenue \| West
Fixed maturities:
Cost or Amortized Cost	124,791	126,521
Gross Unrealized Appreciation	1,879	8,128
Gross Unrealized Depreciation	53	0
Fair Value	126,617	134,649
Allowance for Credit Losses	0	0
Carrying Value	126,617	134,649
Foreign bonds
Fixed maturities:
Cost or Amortized Cost	35,264	30,314
Gross Unrealized Appreciation	226	789
Gross Unrealized Depreciation	1,584	197
Fair Value	33,906	30,906
Allowance for Credit Losses	0	0
Carrying Value	33,906	30,906
Public utilities
Fixed maturities:
Cost or Amortized Cost	117,845	104,008
Gross Unrealized Appreciation	800	3,966
Gross Unrealized Depreciation	3,979	481
Fair Value	114,666	107,493
Allowance for Credit Losses	0	0
Carrying Value	114,666	107,493
Corporate bonds \| Energy
Fixed maturities:
Cost or Amortized Cost	39,143	31,011
Gross Unrealized Appreciation	506	1,751
Gross Unrealized Depreciation	952	81
Fair Value	38,697	32,681
Allowance for Credit Losses	0	0
Carrying Value	38,697	32,681
Corporate bonds \| Industrials
Fixed maturities:
Cost or Amortized Cost	53,976	55,014
Gross Unrealized Appreciation	619	2,319
Gross Unrealized Depreciation	2,219	162
Fair Value	52,376	57,171
Allowance for Credit Losses	0	0
Carrying Value	52,376	57,171
Corporate bonds \| Consumer goods and services
Fixed maturities:
Cost or Amortized Cost	77,509	71,543
Gross Unrealized Appreciation	490	1,912
Gross Unrealized Depreciation	3,933	611
Fair Value	74,066	72,844
Allowance for Credit Losses	0	0
Carrying Value	74,066	72,844
Corporate bonds \| Health care
Fixed maturities:
Cost or Amortized Cost	28,314	27,351
Gross Unrealized Appreciation	158	539
Gross Unrealized Depreciation	2,496	461
Fair Value	25,976	27,429
Allowance for Credit Losses	0	0
Carrying Value	25,976	27,429
Corporate bonds \| Technology, media and telecommunications
Fixed maturities:
Cost or Amortized Cost	62,204	55,405
Gross Unrealized Appreciation	847	2,958
Gross Unrealized Depreciation	2,881	866
Fair Value	60,170	57,497
Allowance for Credit Losses	0	0
Carrying Value	60,170	57,497
Corporate bonds \| Financial services
Fixed maturities:
Cost or Amortized Cost	119,478	98,352
Gross Unrealized Appreciation	1,160	4,394
Gross Unrealized Depreciation	2,035	131
Fair Value	118,603	102,615
Allowance for Credit Losses	0	0
Carrying Value	118,603	102,615
Mortgage-backed securities
Fixed maturities:
Cost or Amortized Cost	23,293	25,075
Gross Unrealized Appreciation	35	167
Gross Unrealized Depreciation	1,310	229
Fair Value	22,018	25,013
Allowance for Credit Losses	0	0
Carrying Value	22,018	25,013
Collateralized mortgage obligations \| Government national mortgage association
Fixed maturities:
Cost or Amortized Cost	102,710	109,968
Gross Unrealized Appreciation	148	2,322
Gross Unrealized Depreciation	4,856	1,772
Fair Value	98,002	110,518
Allowance for Credit Losses	0	0
Carrying Value	98,002	110,518
Collateralized mortgage obligations \| Federal home loan mortgage corporation
Fixed maturities:
Cost or Amortized Cost	104,844	120,911
Gross Unrealized Appreciation	53	736
Gross Unrealized Depreciation	4,926	1,658
Fair Value	99,971	119,989
Allowance for Credit Losses	0	0
Carrying Value	99,971	119,989
Collateralized mortgage obligations \| Federal national mortgage association
Fixed maturities:
Cost or Amortized Cost	45,160	48,246
Gross Unrealized Appreciation	217	945
Gross Unrealized Depreciation	1,916	642
Fair Value	43,461	48,549
Allowance for Credit Losses	0	0
Carrying Value	43,461	48,549
Asset-backed securities
Fixed maturities:
Cost or Amortized Cost	327	325
Gross Unrealized Appreciation	562	600
Gross Unrealized Depreciation	0	0
Fair Value	889	925
Allowance for Credit Losses	0	0
Carrying Value	$ 889	$ 925

Debt Securities, Available-for-Sale, Excluding Accrued Interest, Before Allowance For Credit Loss

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- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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-Section 50
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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
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Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
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