Investments - Schedule of Available-for-sale and Held-to-Maturity Securities Reconciliation (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 65,679	$ 73,749
Gross Unrealized Gains	16	85
Gross Unrealized Losses	(1,761)	(376)
Fair Value	63,934	73,458
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	733,279	647,141
Gross Unrealized Gains	1,487	1,407
Gross Unrealized Losses	(13,397)	(7,166)
Fair Value	721,369	641,382
US Treasury Bill Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,962
Gross Unrealized Gains	0
Gross Unrealized Losses	(37)
Fair Value	9,925
Obligations of U.S. Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	99,926	99,878
Gross Unrealized Gains	0	6
Gross Unrealized Losses	(1,428)	(660)
Fair Value	98,498	99,224
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	26,566	34,181
Gross Unrealized Gains	327	674
Gross Unrealized Losses	(83)	(213)
Fair Value	26,810	34,642
Residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	596,825	513,082
Gross Unrealized Gains	1,160	727
Gross Unrealized Losses	(11,849)	(6,293)
Fair Value	586,136	507,516
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	12,506	14,031
Gross Unrealized Gains	16	69
Gross Unrealized Losses	(114)	(46)
Fair Value	12,408	14,054
Residential mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	53,173	59,718
Gross Unrealized Gains	0	16
Gross Unrealized Losses	(1,647)	(330)
Fair Value	$ 51,526	$ 59,404

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

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