Fair Value (Fair value measurement non-recurring) (Details) (Nonrecurring Basis, USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	$ 10,863		$ 19,345
Other real estate owned	19,097		19,016
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Other real estate owned	0		0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Other real estate owned	0		0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	10,863		19,345
Other real estate owned	19,097	[1]	19,016	[1]
Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	68		1,033
Commercial | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Commercial | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Commercial | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	68	[1]	1,033	[1]
Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	6,285		12,584
Commercial real estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Commercial real estate | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Commercial real estate | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	6,285	[1]	12,584	[1]
Agricultural and agricultural real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	276		552
Agricultural and agricultural real estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Agricultural and agricultural real estate | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Agricultural and agricultural real estate | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	276	[1]	552	[1]
Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	2,474		3,173
Residential real estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Residential real estate | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Residential real estate | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	2,474	[1]	3,173	[1]
Consumer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,760		2,003
Consumer | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Consumer | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Consumer | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,760	[1]	2,003	[1]
Year-to- Date Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	354		3,402
Other real estate owned	361		1,938
Year-to- Date Losses | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		659
Year-to- Date Losses | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	78		492
Year-to- Date Losses | Agricultural and agricultural real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	276		2,229
Year-to- Date Losses | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0		0
Year-to- Date Losses | Consumer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	$ 0		$ 22

[1] Third party appraisals are obtained as to the value of the underlying asset, but disclosure of this information would not provide meaningful information, as the range will vary widely from loan to loan. Types of discounts considered included age of the appraisal, local market conditions, current condition of the property, and estimated sales costs. These discounts will also vary from loan to loan, thus providing range would not be meaningful.