Securities - Narrative (Details)	3 Months Ended
Mar. 31, 2019 USD ($) security institution	Dec. 31, 2018 USD ($)
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 1,255,353,000	$ 1,250,777,000
Number of institutions issuing debt \| institution	150
Secure government, public and trust deposits
Debt Securities, Available-for-sale [Line Items]
Available for sale securities pledged as collateral	$ 553,451,000	619,308,000
Short-term borrowings
Debt Securities, Available-for-sale [Line Items]
Available for sale securities pledged as collateral	19,629,000	18,299,000
Trust preferred securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 10,246,000	$ 10,633,000
Number of securities representing interests in tranches of trusts (tranches) \| security	2
Impairments	$ 0

Number of institutions issuing debt.

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- Definition

Number of securities representing interests in tranches of trusts.

+ References

No definition available.

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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- Definition

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284422-111562

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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