Shareholders' Equity (Regulatory Captial Requirements) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital	$ 304,196		$ 304,716
Total Capital to Risk-Weighted Assets	13.06%		13.26%
Total Capital for Capital Adequacy Purposes	186,380		183,876
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets	8.00%		8.00%
Total Capital To Be Well Capitalized	232,974		229,845
Total Capital To Be Well Capitalized to Risk Weighted-Assets	10.00%		10.00%
Tier 1 Capital	276,038		275,956
Tier 1 Capital to Risk Weighted-Assets	11.85%		12.01%
Tier 1 Capital Required For Capital Adequacy Purposes	93,190		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	139,785		137,907
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets	6.00%		6.00%
Tier 1 Leverage Capital	276,038	[1]	275,956	[1]
Tier 1 Leverage Capital to Average Assets	9.32%	[1]	9.30%	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	118,473	[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	148,091	[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	298,406		299,503
Total Capital to Risk-Weighted Assets	12.82%		13.05%
Total Capital for Capital Adequacy Purposes	186,206		183,651
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets	8.00%		8.00%
Total Capital To Be Well Capitalized	232,758		229,564
Total Capital To Be Well Capitalized to Risk Weighted-Assets	10.00%		10.00%
Tier 1 Capital	270,248		270,778
Tier 1 Capital to Risk Weighted-Assets	11.61%		11.80%
Tier 1 Capital Required For Capital Adequacy Purposes	93,103		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	139,655		137,738
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets	6.00%		6.00%
Tier 1 Leverage Capital	270,248	[1]	270,778	[1]
Tier 1 Leverage Capital to Average Assets	9.14%	[1]	9.14%	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	118,271	[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	$ 147,839	[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