INVESTMENTS - Fair Value of Investments (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Fixed Maturity, Available-for-sale
Amortized Cost	$ 2,239,173,000	$ 1,961,531,000
Gross Unrealized Gain	23,900,000	3,640,000
Gross Unrealized Loss	57,723,000	96,840,000
Allowance for Credit Losses	0	0
Fair Value	2,205,350,000	1,868,331,000
US Treasury and government agencies
Fixed Maturity, Available-for-sale
Amortized Cost	109,358,000	126,402,000
Gross Unrealized Gain	482,000	153,000
Gross Unrealized Loss	5,736,000	9,255,000
Allowance for Credit Losses	0	0
Fair Value	104,104,000	117,301,000
States, municipalities and political subdivisions
Fixed Maturity, Available-for-sale
Amortized Cost	261,711,000	252,936,000
Gross Unrealized Gain	1,598,000	52,000
Gross Unrealized Loss	1,575,000	5,084,000
Allowance for Credit Losses	0	0
Fair Value	261,734,000	247,904,000
Corporate
Fixed Maturity, Available-for-sale
Amortized Cost	797,892,000	728,662,000
Gross Unrealized Gain	9,186,000	1,354,000
Gross Unrealized Loss	23,924,000	40,633,000
Allowance for Credit Losses	0	0
Fair Value	783,154,000	689,382,000
Residential mortgage-backed
Fixed Maturity, Available-for-sale
Amortized Cost	732,452,000	623,431,000
Gross Unrealized Gain	8,991,000	864,000
Gross Unrealized Loss	25,846,000	40,884,000
Allowance for Credit Losses	0	0
Fair Value	715,597,000	583,411,000
Commercial mortgage-backed
Fixed Maturity, Available-for-sale
Amortized Cost	143,009,000	102,975,000
Gross Unrealized Gain	2,405,000	624,000
Gross Unrealized Loss	7,000	44,000
Allowance for Credit Losses	0	0
Fair Value	145,407,000	103,554,000
Other asset-backed
Fixed Maturity, Available-for-sale
Amortized Cost	194,751,000	127,125,000
Gross Unrealized Gain	1,238,000	593,000
Gross Unrealized Loss	635,000	940,000
Allowance for Credit Losses	0	0
Fair Value	$ 195,354,000	$ 126,779,000

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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- Definition

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://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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- References

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- Definition

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
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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- Definition

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).

+ References

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