Loans and Leases (Troubled debt restructurings on financing receivables) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 loans	Jun. 30, 2012 loans	Jun. 30, 2013 loans	Jun. 30, 2012 loans
Financing Receivable, Modifications [Line Items]
Number of loans	4	5	10	6
Pre-modification recorded investment	$ 13,419	$ 3,399	$ 21,311	$ 3,417
Post-modification recorded investment	13,419	3,399	21,311	3,417
Commercial Portfolio Segment
Financing Receivable, Modifications [Line Items]
Number of loans	2	1	3	2
Pre-modification recorded investment	13,203	1,380	17,873	1,398
Post-modification recorded investment	13,203	1,380	17,873	1,398
Agricultural Portfolio Segment
Financing Receivable, Modifications [Line Items]
Number of loans	0	3	3	3
Pre-modification recorded investment	0	1,014	2,576	1,014
Post-modification recorded investment	0	1,014	2,576	1,014
Residential Portfolio Segment
Financing Receivable, Modifications [Line Items]
Number of loans	1	1	3	1
Pre-modification recorded investment	50	1,005	696	1,005
Post-modification recorded investment	50	1,005	696	1,005
Consumer Portfolio Segment
Financing Receivable, Modifications [Line Items]
Number of loans	1	0	1	0
Pre-modification recorded investment	166	0	166	0
Post-modification recorded investment	166	0	166	0
Commercial | Commercial Portfolio Segment
Financing Receivable, Modifications [Line Items]
Number of loans	2	0	3	0
Pre-modification recorded investment	13,203	0	17,873	0
Post-modification recorded investment	13,203	0	17,873	0
Commercial Real Estate | Commercial Portfolio Segment
Financing Receivable, Modifications [Line Items]
Number of loans	0	1	0	2
Pre-modification recorded investment	0	1,380	0	1,398
Post-modification recorded investment	$ 0	$ 1,380	$ 0	$ 1,398