Shareholders' Equity (Regulatory Captial Requirements) (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Corporation [Member]
Total Capital (to Risk-Weighted Assets):
Total Capital		$ 370,559	$ 367,443
Total Capital to Risk-Weighted Assets		12.45%	12.58%
Total Capital for Capital Adequacy Purposes		$ 238,171	$ 233,739
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		8.00%	8.00%
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 344,233	$ 340,130
Tier 1 Capital to Risk Weighted-Assets		11.56%	11.64%
Tier 1 Capital Required For Capital Adequacy Purposes		$ 178,628	$ 175,304
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		$ 322,234	$ 318,131
Common Equity Tier 1 Capital to Risk Weighted Assets		10.82%	10.89%
Common Equity Tier 1 Capital Required for Capital Adequacy		$ 133,971	$ 131,478
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]	$ 344,233	$ 340,130
Tier 1 Leverage Capital to Average Assets	[1]	9.31%	9.37%
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 147,911	$ 145,191
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		$ 370,254	$ 366,676
Total Capital to Risk-Weighted Assets		12.44%	12.55%
Total Capital for Capital Adequacy Purposes		$ 238,110	$ 233,676
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		8.00%	8.00%
Total Capital To Be Well Capitalized		$ 297,638	$ 292,095
Total Capital To Be Well Capitalized to Risk Weighted-Assets		10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 343,928	$ 339,363
Tier 1 Capital to Risk Weighted-Assets		11.56%	11.62%
Tier 1 Capital Required For Capital Adequacy Purposes		$ 178,583	$ 175,257
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets		6.00%	6.00%
Tier 1 Capital Required To Be Well Capitalized		$ 238,110	$ 233,676
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		$ 343,928	$ 339,363
Common Equity Tier 1 Capital to Risk Weighted Assets		11.56%	11.62%
Common Equity Tier 1 Capital Required for Capital Adequacy		$ 133,937	$ 131,443
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		$ 193,464	$ 189,861
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]	$ 343,928	$ 339,363
Tier 1 Leverage Capital to Average Assets	[1]	9.31%	9.36%
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 147,834	$ 145,103
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]	$ 184,793	$ 181,378
Tier 1 Leverage Capital Required To Be Well Capitalized to Average Assets	[1]	5.00%	5.00%

[1] Leverage ratio.