Fair Value - Assets and liabilities measured at fair value on a nonrecurring basis - (Details) - Nonrecurring basis - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
OREO
Fair Value
Other Real Estate	$ 11,073	$ 20,007	$ 11,203
Non-acquired Credit Impaired loans
Fair Value
Other Real Estate	2,118	2,290	10,495
Significant Unobservable Inputs (Level 3) \| OREO
Fair Value
Other Real Estate	11,073	20,007	11,203
Significant Unobservable Inputs (Level 3) \| Non-acquired Credit Impaired loans
Fair Value
Other Real Estate	$ 2,118	$ 2,290	$ 10,495
Significant Unobservable Inputs (Level 3) \| Discounted appraisals \| Impaired loans
Quantitative Information about Level 3 Fair Value Measurements
Collateral discounts (as a percent)	3.00%	6.00%	3.00%
Significant Unobservable Inputs (Level 3) \| Discounted appraisals \| OREO
Quantitative Information about Level 3 Fair Value Measurements
Collateral discounts and estimated costs to sell (as a percent)	28.00%	20.00%	21.00%

Percentage rate based on collateral discounts and estimated costs to sell.

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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

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- References

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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(4))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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