Loans (Troubled debt restructuring) (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017 USD ($) loan	Sep. 30, 2016 USD ($) loan	Sep. 30, 2017 USD ($) loan	Sep. 30, 2016 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of Loans \| loan	8	5	25	7
Pre- Modification Recorded Investment	$ 1,174	$ 651	$ 3,108	$ 930
Post- Modification Recorded Investment	$ 1,174	$ 651	$ 3,108	$ 930
With Payment Defaults During the Following Periods
Number of Loans \| loan	5	0	8	1
Recorded Investment	$ 1,221	$ 0	$ 1,480	$ 95
Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans \| loan	0	0	3	2
Pre- Modification Recorded Investment	$ 0	$ 0	$ 131	$ 279
Post- Modification Recorded Investment	$ 0	$ 0	$ 131	$ 279
With Payment Defaults During the Following Periods
Number of Loans \| loan	0	0	0	1
Recorded Investment	$ 0	$ 0	$ 0	$ 95
Commercial \| Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans \| loan	0	0	3	1
Pre- Modification Recorded Investment	$ 0	$ 0	$ 131	$ 100
Post- Modification Recorded Investment	$ 0	$ 0	$ 131	$ 100
With Payment Defaults During the Following Periods
Number of Loans \| loan	0	0	0	1
Recorded Investment	$ 0	$ 0	$ 0	$ 95
Commercial \| Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans \| loan	0	0	0	1
Pre- Modification Recorded Investment	$ 0	$ 0	$ 0	$ 179
Post- Modification Recorded Investment	$ 0	$ 0	$ 0	$ 179
With Payment Defaults During the Following Periods
Number of Loans \| loan	0	0	0	0
Recorded Investment	$ 0	$ 0	$ 0	$ 0
Agricultural and agricultural real estate
Financing Receivable, Modifications [Line Items]
Number of Loans \| loan	0	0	0	0
Pre- Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
Post- Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
With Payment Defaults During the Following Periods
Number of Loans \| loan	0	0	0	0
Recorded Investment	$ 0	$ 0	$ 0	$ 0
Residential real estate
Financing Receivable, Modifications [Line Items]
Number of Loans \| loan	8	5	22	5
Pre- Modification Recorded Investment	$ 1,174	$ 651	$ 2,977	$ 651
Post- Modification Recorded Investment	$ 1,174	$ 651	$ 2,977	$ 651
With Payment Defaults During the Following Periods
Number of Loans \| loan	5	0	8	0
Recorded Investment	$ 1,221	$ 0	$ 1,480	$ 0
Consumer
Financing Receivable, Modifications [Line Items]
Number of Loans \| loan	0	0	0	0
Pre- Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
Post- Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
With Payment Defaults During the Following Periods
Number of Loans \| loan	0	0	0	0
Recorded Investment	$ 0	$ 0	$ 0	$ 0

Financing Receivable, Subsequent Default [Abstract]

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Number of 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 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

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Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

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Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

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