Fair Value (Fair Value Measurement Non-recurring) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Premises, furniture and equipment held for sale	$ 7,258				$ 1,977				$ 7,258	$ 1,977
Benefit to provision for loan losses	(9,681)	$ (5,238)	$ (4,831)	$ (4,263)	(5,328)	$ (5,705)	$ (889)	$ (3,641)	(24,013)	(15,563)	$ (11,694)
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0				0				0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	52,577				44,560				52,577	44,560
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	67,224				0				67,224	0
Nonrecurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	25,509				23,469				25,509	23,469
Loans held for sale	119,801				44,560				119,801	44,560
Other real estate owned	6,153				10,777				6,153	10,777
Premises, furniture and equipment held for sale	7,258				1,977				7,258	1,977
Nonrecurring Basis | (Gains)/Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	1,307				3,469				1,307	3,469
Loans held for sale	(1,870)				190				(1,870)	190
Other real estate owned	2,647				737				2,647	737
Premises, furniture and equipment held for sale	59				192				59	192
Nonrecurring Basis | 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				0	0
Loans held for sale	0				0				0	0
Other real estate owned	0				0				0	0
Premises, furniture and equipment held for sale	0				0				0	0
Nonrecurring Basis | 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				0	0
Loans held for sale	52,577				44,560				52,577	44,560
Other real estate owned	0				0				0	0
Premises, furniture and equipment held for sale	0				0				0	0
Nonrecurring Basis | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	25,509				23,469				25,509	23,469
Loans held for sale	67,224				0				67,224	0
Other real estate owned	6,153				10,777				6,153	10,777
Premises, furniture and equipment held for sale	7,258				1,977				7,258	1,977
Benefit to provision for loan losses									953
Nonrecurring Basis | Commercial Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	7,143				291				7,143	291
Nonrecurring Basis | Commercial Servicing Rights | (Gains)/Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	58				(21)				58	(21)
Nonrecurring Basis | Commercial Servicing Rights | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	0				0				0	0
Nonrecurring Basis | Commercial Servicing Rights | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	0				0				0	0
Nonrecurring Basis | Commercial Servicing Rights | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rights	7,143				291				7,143	291
Nonrecurring Basis | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	12,932				3,212				12,932	3,212
Nonrecurring Basis | Commercial | (Gains)/Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	660				1,119				660	1,119
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | Commercial | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	12,932				3,212				12,932	3,212
Nonrecurring Basis | Commercial Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	405				9,480				405	9,480
Nonrecurring Basis | Commercial Real Estate | (Gains)/Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	72				322				72	322
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | 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	405				9,480				405	9,480
Nonrecurring Basis | Agricultural and Agricultural Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	11,070				8,406				11,070	8,406
Nonrecurring Basis | Agricultural and Agricultural Real Estate | (Gains)/Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	575				2,028				575	2,028
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | 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	11,070				8,406				11,070	8,406
Nonrecurring Basis | Residential Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	478				1,137				478	1,137
Nonrecurring Basis | Residential Real Estate | (Gains)/Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0				0				0	0
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | 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	478				1,137				478	1,137
Nonrecurring Basis | Consumer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	624				1,234				624	1,234
Nonrecurring Basis | Consumer | (Gains)/Losses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0				0				0	0
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | 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				0	0
Nonrecurring Basis | Consumer | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	$ 624				$ 1,234				$ 624	$ 1,234