Fair Value (Assets and liabilities on recurring and non-recurring basis) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 645,797,000	$ 751,484,000
Money Market Funds, at Carrying Value	7,021,000	5,606,000
Trading Securities	191,000	347,000
Derivative Assets	771,000	1,330,000
Servicing Assets	9,821,000	9,858,000	$ 7,455,000	$ 13,992,000
Derivative liabilities	(1,281,000)	(2,437,000)
Total	662,320,000	766,188,000
Impaired Commercial Loan	72,285,000	54,289,000
Foreclosed real estate	44,174,000	47,520,000	$ 58,176,000	$ 95,750,000
Other repossessed assets	3,548,000	3,224,000
Total	120,007,000	105,033,000
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Money Market Funds, at Carrying Value	7,021,000	5,606,000
Trading Securities	0	0
Derivative Assets	0	0
Servicing Assets	0	0
Derivative liabilities	0	0
Total	7,021,000	5,606,000
Impaired Commercial Loan	0	0
Foreclosed real estate	0	0
Other repossessed assets	0	0
Total	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	645,797,000	751,484,000
Money Market Funds, at Carrying Value	0	0
Trading Securities	191,000	347,000
Derivative Assets	771,000	1,330,000
Servicing Assets	0	0
Derivative liabilities	(1,281,000)	(2,437,000)
Total	645,478,000	750,724,000
Impaired Commercial Loan	0	0
Foreclosed real estate	0	0
Other repossessed assets	0	0
Total	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Money Market Funds, at Carrying Value	0	0
Trading Securities	0	0
Derivative Assets	0	0
Servicing Assets	9,821,000	9,858,000
Derivative liabilities	0	0
Total	9,821,000	9,858,000
Impaired Commercial Loan	72,285,000	54,289,000
Foreclosed real estate	44,174,000	47,520,000
Other repossessed assets	3,548,000	3,224,000
Total	120,007,000	105,033,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	645,797,000	751,484,000
Money Market Funds, at Carrying Value	7,021,000	5,606,000
Trading Securities	191,000	347,000
Derivative Assets	771,000	1,330,000
Servicing Assets	9,821,000	9,858,000
Derivative liabilities	(1,281,000)	(2,437,000)
Total	662,320,000	766,188,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Money Market Funds, at Carrying Value	7,021,000	5,606,000
Trading Securities	0	0
Derivative Assets	0	0
Servicing Assets	0	0
Derivative liabilities	0	0
Total	7,021,000	5,606,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	645,797,000	751,484,000
Money Market Funds, at Carrying Value	0	0
Trading Securities	191,000	347,000
Derivative Assets	771,000	1,330,000
Servicing Assets	0	0
Derivative liabilities	(1,281,000)	(2,437,000)
Total	645,478,000	750,724,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Money Market Funds, at Carrying Value	0	0
Trading Securities	0	0
Derivative Assets	0	0
Servicing Assets	9,821,000	9,858,000
Derivative liabilities	0	0
Total	9,821,000	9,858,000
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Commercial Loan	72,285,000	54,289,000
Foreclosed real estate	44,174,000	47,520,000
Other repossessed assets	3,548,000	3,224,000
Total	120,007,000	105,033,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Commercial Loan	0	0
Foreclosed real estate	0	0
Other repossessed assets	0	0
Total	0	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Commercial Loan	0	0
Foreclosed real estate	0	0
Other repossessed assets	0	0
Total	0	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Commercial Loan	72,285,000	54,289,000
Foreclosed real estate	44,174,000	47,520,000
Other repossessed assets	3,548,000	3,224,000
Total	$ 120,007,000	$ 105,033,000