INVESTMENTS (Summary of Amortized Cost and Fair Value of Debt and Equity Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt securities - available-for-sale:
Amortized Cost of Cost	$ 406,173	$ 473,126
Fair Value	411,718	488,210
Debt Securities
Debt securities - available-for-sale:
Amortized Cost of Cost	406,173	473,126
Gross Unrealized Gains	9,862	15,218
Gross Unrealized Losses	4,317	134
Fair Value	411,718	488,210
United States government obligations and authorities
Debt securities - available-for-sale:
Amortized Cost of Cost	123,451	169,947
Gross Unrealized Gains	1,273	1,866
Gross Unrealized Losses	939	38
Fair Value	123,785	171,775
Obligations of states and political subdivisions
Debt securities - available-for-sale:
Amortized Cost of Cost	21,844	21,560
Gross Unrealized Gains	532	704
Gross Unrealized Losses	153	0
Fair Value	22,223	22,264
Corporate securities
Debt securities - available-for-sale:
Amortized Cost of Cost	232,168	254,618
Gross Unrealized Gains	7,663	11,989
Gross Unrealized Losses	2,975	79
Fair Value	236,856	266,528
International securities
Debt securities - available-for-sale:
Amortized Cost of Cost	28,710	27,001
Gross Unrealized Gains	394	659
Gross Unrealized Losses	250	17
Fair Value	$ 28,854	$ 27,643

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).

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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).

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Amortized cost 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 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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