INVESTMENTS (Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity) (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
One year or less	$ 18,875
Over one through five years	195,641
Over five through ten years	132,764
Over ten years	172,277
Amortized Cost	519,557
Available-for-sale Securities, Debt maturities, Fair value:
One year or less	19,022
Over one through five years	203,440
Over five through ten years	140,422
Over ten years	177,559
Fair Value	$ 540,443

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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