SUMMARY OF INVESTMENTS (Maturities) (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Available-For-Sale, Amortized Cost
Due in one year or less	$ 32,214
Due after one year through five years	476,667
Due after five years through 10 years	400,277
Due after 10 years	475,442
Available-For-Sale, Fair Value
Due in one year or less	32,467
Due after one year through five years	502,699
Due after five years through 10 years	431,271
Due after 10 years	515,226
Fixed maturities
Available-For-Sale, Amortized Cost
Securities not categorized by contractual maturity	1,720,291
Available-For-Sale, Fair Value
Securities not categorized by contractual maturity	1,825,443
Asset-backed securities
Available-For-Sale, Amortized Cost
Securities not categorized by contractual maturity	314
Available-For-Sale, Fair Value
Securities not categorized by contractual maturity	926
Mortgage-backed securities
Available-For-Sale, Amortized Cost
Securities not categorized by contractual maturity	20,305
Available-For-Sale, Fair Value
Securities not categorized by contractual maturity	20,577
Collateralized mortgage obligations
Available-For-Sale, Amortized Cost
Securities not categorized by contractual maturity	315,072
Available-For-Sale, Fair Value
Securities not categorized by contractual maturity	$ 322,277

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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