Investments - Amortized Cost and Estimated Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	$ 576,363	$ 592,378
Gross Unrealized Gains	22,982	9,956
Gross Unrealized Losses	(12)	(1,535)
Estimated Fair Value	599,333	600,799
U.S. Government Agencies [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	1,775	12,125
Gross Unrealized Gains	75	124
Gross Unrealized Losses		(104)
Estimated Fair Value	1,850	12,145
Mortgage-backed Securities [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	364,828	398,353
Gross Unrealized Gains	10,668	3,354
Gross Unrealized Losses	(11)	(1,318)
Estimated Fair Value	375,485	400,389
States and Political Subdivisions [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	209,760	181,900
Gross Unrealized Gains	12,239	6,478
Gross Unrealized Losses	(1)	(113)
Estimated Fair Value	$ 221,998	$ 188,265

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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+ References

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