Non Purchased Loans - Narrative (Details)	6 Months Ended
Jun. 30, 2018 USD ($) loan	Jun. 30, 2017 USD ($) loan	Dec. 31, 2017 USD ($)
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Allowance for loan losses attributable to restructured loans	$ 47,355,000		$ 46,211,000
Non purchased loans and leases
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Mortgage and commercial loans discontinued past due period	90 days
Consumer and other retail loans charged-off past due period	120 days
Threshold for impairment measurement	$ 500,000
Troubled debt restructured	$ 4,685,000	$ 156,000	$ 5,588,000
Nonperforming loans charged-off past due period	90 days
Number of restructured loans \| loan	2	1
Restructured loans discontinued past due period	90 days	90 days
Remaining availability under commitments to lend additional funds on restructured loans	$ 22,000	$ 0
Non purchased loans and leases \| Nonaccruing Loans
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Outstanding balance of restructured loans	468,000	71,000
Non purchased loans and leases \| Restructured Loans
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Outstanding balance of restructured loans	2,417,000	4,409,000
Allowance for loan losses attributable to restructured loans	$ 37,000	$ 238,000

Consumer and other retail loans charged off past due period.

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Financing Receivable, Threshold for Impairment Measurement

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Loans and the allowance for loan losses.

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Mortgage and commercial loans discontinued past due period.

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Nonperforming loans charged off past due period.

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Number of Restructured Loans

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Maximum duration past due for restructured loans to be considered performing.

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The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
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Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18794-111554

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a))
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