Shareholders' Equity (Regulatory Captial Requirements) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital	$ 298,553		$ 279,751
Total Capital to Risk-Weighted Assets	13.18%		12.86%
Total Capital for Capital Adequacy Purposes	181,218		174,073
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets	8.00%		8.00%
Total Capital To Be Well Capitalized	226,522		217,592
Total Capital To Be Well Capitalized to Risk Weighted-Assets	10.00%		10.00%
Tier 1 Capital	270,204		252,516
Tier 1 Capital to Risk Weighted-Assets	11.93%		11.61%
Tier 1 Capital Required For Capital Adequacy Purposes	90,609		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	135,913		130,555
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets	6.00%		6.00%
Tier 1 Leverage Capital	270,204	[1]	252,516	[1]
Tier 1 Leverage Capital to Average Assets	9.11%	[1]	8.70%	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	118,644	[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	148,305	[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	293,508		275,183
Total Capital to Risk-Weighted Assets	12.97%		12.66%
Total Capital for Capital Adequacy Purposes	180,995		173,845
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets	8.00%		8.00%
Total Capital To Be Well Capitalized	226,244		217,307
Total Capital To Be Well Capitalized to Risk Weighted-Assets	10.00%		10.00%
Tier 1 Capital	265,194		247,983
Tier 1 Capital to Risk Weighted-Assets	11.72%		11.41%
Tier 1 Capital Required For Capital Adequacy Purposes	90,498		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	135,746		130,384
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets	6.00%		6.00%
Tier 1 Leverage Capital	265,194	[1]	247,983	[1]
Tier 1 Leverage Capital to Average Assets	8.96%	[1]	8.55%	[1]
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	118,452	[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	$ 148,065	[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