Securities - (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Amortized cost and fair value of securities held to maturity
Amortized Cost	$ 339,619	$ 356,282
Gross Unrealized Gains	13,663	8,576
Gross Unrealized Losses	(218)	(1,965)
Fair Value	353,064	362,893
Obligations of other U.S. Government agencies and corporations
Amortized cost and fair value of securities held to maturity
Amortized Cost	12,602	14,101
Gross Unrealized Gains	6	4
Gross Unrealized Losses	(77)	(187)
Fair Value	12,531	13,918
Obligations of states and political subdivisions
Amortized cost and fair value of securities held to maturity
Amortized Cost	327,017	342,181
Gross Unrealized Gains	13,657	8,572
Gross Unrealized Losses	(141)	(1,778)
Fair Value	$ 340,533	$ 348,975

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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Amount before other than temporary impairment (OTTI) accretion, of 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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
-Paragraph 5
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
-Paragraph 5
-Subparagraph (a)
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