Shareholders' Equity (Regulatory Captial Requirements) (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Corporation [Member]
Total Capital (to Risk-Weighted Assets):
Total Capital		$ 527,140	$ 494,603
Total Capital to Risk-Weighted Assets		13.09%	12.94%
Total Capital for Capital Adequacy Purposes		$ 322,243	$ 305,728
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		8.00%	8.00%
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 492,683	$ 467,296
Tier 1 Capital to Risk Weighted-Assets		12.23%	12.23%
Tier 1 Capital Required For Capital Adequacy Purposes		$ 241,682	$ 229,296
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		$ 470,684	$ 445,298
Common Equity Tier 1 Capital to Risk Weighted Assets		11.69%	11.65%
Common Equity Tier 1 Capital Required for Capital Adequacy		$ 181,262	$ 171,972
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]	$ 492,683	$ 467,296
Tier 1 Leverage Capital to Average Assets	[1]	8.77%	9.04%
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 224,714	$ 206,682
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		$ 524,468	$ 490,993
Total Capital to Risk-Weighted Assets		13.02%	12.85%
Total Capital for Capital Adequacy Purposes		$ 322,164	$ 305,693
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		8.00%	8.00%
Total Capital To Be Well Capitalized		$ 402,705	$ 382,116
Total Capital To Be Well Capitalized to Risk Weighted-Assets		10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 490,011	$ 463,686
Tier 1 Capital to Risk Weighted-Assets		12.17%	12.13%
Tier 1 Capital Required For Capital Adequacy Purposes		$ 241,623	$ 229,270
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets		6.00%	6.00%
Tier 1 Capital Required To Be Well Capitalized		$ 322,164	$ 305,693
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		$ 490,011	$ 463,686
Common Equity Tier 1 Capital to Risk Weighted Assets		12.17%	12.13%
Common Equity Tier 1 Capital Required for Capital Adequacy		$ 181,217	$ 171,952
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		$ 261,758	$ 248,375
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]	$ 490,011	$ 463,686
Tier 1 Leverage Capital to Average Assets	[1]	8.73%	8.98%
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 224,625	$ 206,596
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]	$ 280,782	$ 258,245
Tier 1 Leverage Capital Required To Be Well Capitalized to Average Assets	[1]	5.00%	5.00%

[1] Leverage ratio.