Shareholders' Equity (Regulatory Captial Requirements) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital	$ 313,239		$ 304,716
Total Capital to Risk-Weighted Assets	13.44%		13.26%
Total Capital for Capital Adequacy Purposes	186,384		183,876
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets	8.00%		8.00%
Total Capital To Be Well Capitalized	232,980		229,845
Total Capital To Be Well Capitalized to Risk Weighted-Assets	10.00%		10.00%
Tier 1 Capital	284,935		275,956
Tier 1 Capital to Risk Weighted-Assets	12.23%		12.01%
Tier 1 Capital Required For Capital Adequacy Purposes	93,192		91,938
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets	4.00%		4.00%
Tier 1 Capital Required To Be Well Capitalized	139,788		137,907
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets	6.00%		6.00%
Tier 1 Leverage Capital	284,935	[1]	275,956	[1]
Tier 1 Leverage Capital to Average Assets	9.41%	[1]	9.30%	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	121,182	[1]	118,733	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes to Average Assets	4.00%	[1]	4.00%	[1]
Tier 1 Leverage Capital Required To Be Well Capitalized	151,478	[1]	148,417	[1]
Tier 1 Leverage Capital Required To Be Well Capitalized to Average Assets	5.00%	[1]	5.00%	[1]
Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital	308,816		299,503
Total Capital to Risk-Weighted Assets	13.27%		13.05%
Total Capital for Capital Adequacy Purposes	186,227		183,651
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets	8.00%		8.00%
Total Capital To Be Well Capitalized	232,784		229,564
Total Capital To Be Well Capitalized to Risk Weighted-Assets	10.00%		10.00%
Tier 1 Capital	280,512		270,778
Tier 1 Capital to Risk Weighted-Assets	12.05%		11.80%
Tier 1 Capital Required For Capital Adequacy Purposes	93,114		91,826
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets	4.00%		4.00%
Tier 1 Capital Required To Be Well Capitalized	139,670		137,738
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets	6.00%		6.00%
Tier 1 Leverage Capital	280,512	[1]	270,778	[1]
Tier 1 Leverage Capital to Average Assets	9.27%	[1]	9.14%	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	121,013	[1]	118,535	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes to Average Assets	4.00%	[1]	4.00%	[1]
Tier 1 Leverage Capital Required To Be Well Capitalized	$ 151,267	[1]	$ 148,169	[1]
Tier 1 Leverage Capital Required To Be Well Capitalized to Average Assets	5.00%	[1]	5.00%	[1]

[1] Leverage ratio