Investments - Amortized Cost and Estimated Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	$ 591,543	$ 569,942
Gross Unrealized Gains	10,139	1,616
Gross Unrealized Losses	(1,776)	(11,079)
Estimated Fair Value	599,906	560,479
U.S. Government Agencies [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	14,408	15,553
Gross Unrealized Gains	168	12
Gross Unrealized Losses	(131)	(353)
Estimated Fair Value	14,445	15,212
Mortgage-backed Securities [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	409,922	414,208
Gross Unrealized Gains	3,483	398
Gross Unrealized Losses	(1,602)	(9,873)
Estimated Fair Value	411,803	404,733
States and Political Subdivisions [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	167,213	140,181
Gross Unrealized Gains	6,488	1,206
Gross Unrealized Losses	(43)	(853)
Estimated Fair Value	$ 173,658	$ 140,534

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).

+ References

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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).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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