Premises and Equipment (Summary of Premises and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 52,484	$ 48,387
Less accumulated depreciation	30,898	27,301
Total	21,586	21,086
Land [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	873	873
Building [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	13,386	13,087
Leaseholds and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	2,120	2,098
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	14,801	13,248
Software [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	4,819	4,704
Internally Developed Software [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 16,485	$ 14,377