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Securities - Fair Values and Amortized Costs Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	$ 652,785	$ 685,170
Debt Securities, Available-for-Sale, Gross Unrealized Gains	11,816	3,514
Debt Securities, Available-for-Sale, Gross Unrealized Losses	(564)	(8,628)
Debt Securities, Available-for-Sale, Fair Value	664,037	680,056
Marketable equity securities	4,551	4,816
Total Securities	668,588	684,872
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	9,964	9,958
Debt Securities, Available-for-Sale, Gross Unrealized Gains	43	0
Debt Securities, Available-for-Sale, Gross Unrealized Losses	0	(222)
Debt Securities, Available-for-Sale, Fair Value	10,007	9,736
Obligations of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	128,260	129,267
Debt Securities, Available-for-Sale, Gross Unrealized Gains	1,532	68
Debt Securities, Available-for-Sale, Gross Unrealized Losses	(19)	(1,074)
Debt Securities, Available-for-Sale, Fair Value	129,773	128,261
Collateralized mortgage obligations of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	147,692	149,849
Debt Securities, Available-for-Sale, Gross Unrealized Gains	3,029	795
Debt Securities, Available-for-Sale, Gross Unrealized Losses	(316)	(1,985)
Debt Securities, Available-for-Sale, Fair Value	150,405	148,659
Residential mortgage-backed securities of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	20,704	24,564
Debt Securities, Available-for-Sale, Gross Unrealized Gains	289	203
Debt Securities, Available-for-Sale, Gross Unrealized Losses	(57)	(417)
Debt Securities, Available-for-Sale, Fair Value	20,936	24,350
Commercial mortgage-backed securities of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	232,657	251,660
Debt Securities, Available-for-Sale, Gross Unrealized Gains	2,807	0
Debt Securities, Available-for-Sale, Gross Unrealized Losses	(172)	(4,876)
Debt Securities, Available-for-Sale, Fair Value	235,292	246,784
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	113,508	119,872
Debt Securities, Available-for-Sale, Gross Unrealized Gains	4,116	2,448
Debt Securities, Available-for-Sale, Gross Unrealized Losses	0	(54)
Debt Securities, Available-for-Sale, Fair Value	$ 117,624	$ 122,266

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