Loans (Loans Maturing in Portfolio Based on Contractual Terms) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Contract receivable, due within one year	$ 171,033	$ 183,796
Contract receivable, due after one year through five years	232,724	210,999
Contract receivable, due in more than five years	746,287	694,187
Commercial Real Estate Portfolio Segment [Member]
Contract receivable, due within one year	67,951	86,782
Contract receivable, due after one year through five years	150,075	128,431
Contract receivable, due in more than five years	509,288	451,892
Residential First Mortgages Portfolio Segment [Member]
Contract receivable, due within one year	8,596	8,501
Contract receivable, due after one year through five years	35,208	34,592
Contract receivable, due in more than five years	126,570	127,911
Residential Rentals Portfolio Segment [Member]
Contract receivable, due within one year	4,288	3,847
Contract receivable, due after one year through five years	21,627	17,911
Contract receivable, due in more than five years	84,313	80,139
Construction And Land Development Portfolio Segment [Member]
Contract receivable, due within one year	21,226	23,674
Contract receivable, due after one year through five years	6,645	10,212
Contract receivable, due in more than five years		3,048
Home Equity And Second Mortgages Portfolio Segment [Member]
Contract receivable, due within one year	242	296
Contract receivable, due after one year through five years	811	877
Contract receivable, due in more than five years	20,298	20,226
Commercial Portfolio Segment [Member]
Contract receivable, due within one year	56,417	50,484
Consumer Portfolio Segment [Member]
Contract receivable, due within one year	200	163
Contract receivable, due after one year through five years	307	164
Contract receivable, due in more than five years	66	95
Commercial Equipment Portfolio Segment [Member]
Contract receivable, due within one year	12,113	10,049
Contract receivable, due after one year through five years	18,051	18,812
Contract receivable, due in more than five years	$ 5,752	$ 10,876