Investments - Schedule of Available-for-sale and Held-to-Maturity Securities Reconciliation (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 76,168	$ 80,463
Gross Unrealized Gains	252	56
Gross Unrealized Losses	(160)	(880)
Fair Value	76,260	79,639
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	603,491	463,143
Gross Unrealized Gains	2,918	2,079
Gross Unrealized Losses	(3,288)	(4,425)
Fair Value	603,121	460,797
Obligations of U.S. Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	99,866	107,312
Gross Unrealized Gains	271	348
Gross Unrealized Losses	(14)	0
Fair Value	100,123	107,660
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,684	36,486
Gross Unrealized Gains	887	630
Gross Unrealized Losses	(229)	(485)
Fair Value	33,342	36,631
Agency mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	470,941	319,345
Gross Unrealized Gains	1,760	1,101
Gross Unrealized Losses	(3,045)	(3,940)
Fair Value	469,656	316,506
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	14,704	14,759
Gross Unrealized Gains	159	11
Gross Unrealized Losses	(15)	(242)
Fair Value	14,848	14,528
Agency mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	61,464	65,704
Gross Unrealized Gains	93	45
Gross Unrealized Losses	(145)	(638)
Fair Value	$ 61,412	$ 65,111

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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Amount of accumulated unrealized loss 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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