Loans (Troubled debt restructuring on loans modified) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) loan	Sep. 30, 2015 USD ($) loan	Sep. 30, 2016 USD ($) loan	Sep. 30, 2015 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	5	1	7	4
Pre- Modification Recorded Investment	$ 651	$ 55	$ 930	$ 5,188
Post- Modification Recorded Investment	$ 651	$ 55	$ 930	$ 5,188
Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	2	2
Pre- Modification Recorded Investment	$ 0	$ 0	$ 279	$ 4,822
Post- Modification Recorded Investment	$ 0	$ 0	$ 279	$ 4,822
Commercial | Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	1	1
Pre- Modification Recorded Investment	$ 0	$ 0	$ 100	$ 830
Post- Modification Recorded Investment	$ 0	$ 0	$ 100	$ 830
Commercial | Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	1	1
Pre- Modification Recorded Investment	$ 0	$ 0	$ 179	$ 3,992
Post- Modification Recorded Investment	$ 0	$ 0	$ 179	$ 3,992
Agricultural and agricultural real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	0	1
Pre- Modification Recorded Investment	$ 0	$ 0	$ 0	$ 311
Post- Modification Recorded Investment	$ 0	$ 0	$ 0	$ 311
Residential real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	5	1	5	1
Pre- Modification Recorded Investment	$ 651	$ 55	$ 651	$ 55
Post- Modification Recorded Investment	$ 651	$ 55	$ 651	$ 55
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