Shareholders' Equity (Regulatory Captial Requirements) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital	$ 292,179		$ 279,751
Total Capital to Risk-Weighted Assets	13.15%		12.86%
Total Capital for Capital Adequacy Purposes	177,736		174,073
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets	8.00%		8.00%
Total Capital To Be Well Capitalized	222,171		217,592
Total Capital To Be Well Capitalized to Risk Weighted-Assets	10.00%		10.00%
Tier 1 Capital	264,372		252,516
Tier 1 Capital to Risk Weighted-Assets	11.90%		11.61%
Tier 1 Capital Required For Capital Adequacy Purposes	88,868		87,037
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets	4.00%		4.00%
Tier 1 Capital Required To Be Well Capitalized	133,302		130,555
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets	6.00%		6.00%
Tier 1 Leverage Capital	264,372	[1]	252,516	[1]
Tier 1 Leverage Capital to Average Assets	9.00%	[1]	8.70%	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	117,480	[1]	116,158	[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	146,850	[1]	145,198	[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	287,344		275,183
Total Capital to Risk-Weighted Assets	12.95%		12.66%
Total Capital for Capital Adequacy Purposes	177,517		173,845
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets	8.00%		8.00%
Total Capital To Be Well Capitalized	221,896		217,307
Total Capital To Be Well Capitalized to Risk Weighted-Assets	10.00%		10.00%
Tier 1 Capital	259,571		247,983
Tier 1 Capital to Risk Weighted-Assets	11.70%		11.41%
Tier 1 Capital Required For Capital Adequacy Purposes	88,758		86,923
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets	4.00%		4.00%
Tier 1 Capital Required To Be Well Capitalized	133,137		130,384
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets	6.00%		6.00%
Tier 1 Leverage Capital	259,571	[1]	247,983	[1]
Tier 1 Leverage Capital to Average Assets	8.85%	[1]	8.55%	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	117,284	[1]	115,961	[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	$ 146,605	[1]	$ 144,952	[1]
Tier 1 Leverage Capital Required To Be Well Capitalized to Average Assets	5.00%	[1]	5.00%	[1]

[1] Leverage ratio