Shareholders' Equity (Regulatory Captial Requirements) (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Parent Company [Member]
Total Capital (to Risk-Weighted Assets):
Total Capital		$ 416,038	$ 390,867
Total Capital to Risk-Weighted Assets		12.45%	12.26%
Total Capital for Capital Adequacy Purposes		$ 267,365	$ 255,093
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		8.00%	8.00%
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 389,289	$ 364,655
Tier 1 Capital to Risk Weighted-Assets		11.65%	11.44%
Tier 1 Capital Required For Capital Adequacy Purposes		$ 200,524	$ 191,320
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets		6.00%	6.00%
Common Equity Tier 1 Capital [Abstract]
Common Equity Tier 1 Capital		$ 367,291	$ 342,656
Common Equity Tier 1 Capital to Risk Weighted Assets		10.99%	10.75%
Common Equity Tier 1 Required for Capital Adequacy		$ 150,383	$ 143,490
Common Equity Tier 1 Capital for Capital Adequacy to Risk Weighted Assets		4.50%	4.50%
Tier 1 Capital (to Average Assets):
Tier 1 Leverage Capital	[1]	$ 389,289	$ 364,655
Tier 1 Leverage Capital to Average Assets	[1]	8.79%	8.67%
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 177,089	$ 168,271
Tier 1 Leverage Capital Required for Capital Adequacy Purposes to Average Assets	[1]	4.00%	4.00%
Bank [Member]
Total Capital (to Risk-Weighted Assets):
Total Capital		$ 413,593	$ 389,840
Total Capital to Risk-Weighted Assets		12.38%	12.23%
Total Capital for Capital Adequacy Purposes		$ 267,338	$ 255,050
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		8.00%	8.00%
Total Capital To Be Well Capitalized		$ 334,172	$ 318,813
Total Capital To Be Well Capitalized to Risk Weighted-Assets		10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 386,844	$ 363,628
Tier 1 Capital to Risk Weighted-Assets		11.58%	11.41%
Tier 1 Capital Required For Capital Adequacy Purposes		$ 200,503	$ 191,288
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets		6.00%	6.00%
Tier 1 Capital Required To Be Well Capitalized		$ 267,338	$ 255,050
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets		8.00%	8.00%
Common Equity Tier 1 Capital [Abstract]
Common Equity Tier 1 Capital		$ 386,844	$ 363,628
Common Equity Tier 1 Capital to Risk Weighted Assets		11.58%	11.41%
Common Equity Tier 1 Required for Capital Adequacy		$ 150,378	$ 143,466
Common Equity Tier 1 Capital for Capital Adequacy to Risk Weighted Assets		4.50%	4.50%
Common Equity Tier 1 Capital Required to be Well Capitalized		$ 217,212	$ 207,228
Common Equity Tier 1 Capital Required to be Well Capitalized to Risk Weighted Assets		6.50%	6.50%
Tier 1 Capital (to Average Assets):
Tier 1 Leverage Capital	[1]	$ 386,844	$ 363,628
Tier 1 Leverage Capital to Average Assets	[1]	8.74%	8.65%
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 177,048	$ 168,207
Tier 1 Leverage Capital Required for Capital Adequacy Purposes to Average Assets	[1]	4.00%	4.00%
Tier 1 Leverage Capital Required To Be Well Capitalized	[1]	$ 221,310	$ 210,259
Tier 1 Leverage Capital Required To Be Well Capitalized to Average Assets	[1]	5.00%	5.00%

[1] Leverage ratio.