Securities - (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Amortized cost and fair value of securities held to maturity
Amortized Cost	$ 389,145	$ 458,400
Gross Unrealized Gains	20,644	16,662
Gross Unrealized Losses	(21)	(1,309)
Fair Value	409,768	473,753
Obligations of other U.S. Government agencies and corporations
Amortized cost and fair value of securities held to maturity
Amortized Cost	34,093	101,155
Gross Unrealized Gains	49	26
Gross Unrealized Losses	(15)	(1,214)
Fair Value	34,127	99,967
Obligations of states and political subdivisions
Amortized cost and fair value of securities held to maturity
Amortized Cost	355,052	357,245
Gross Unrealized Gains	20,595	16,636
Gross Unrealized Losses	(6)	(95)
Fair Value	$ 375,641	$ 373,786

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=73527792&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

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