Shareholders' Equity (Regulatory Captial Requirements) (Details) - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Corporation [Member]
Total Capital (to Risk-Weighted Assets):
Total Capital		$ 475,982	$ 455,699
Total Capital to Risk-Weighted Assets		12.80%	12.56%
Total Capital for Capital Adequacy Purposes		$ 297,470	$ 290,146
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		8.00%	8.00%
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 448,282	$ 428,338
Tier 1 Capital to Risk Weighted-Assets		12.06%	11.81%
Tier 1 Capital Required For Capital Adequacy Purposes		$ 223,102	$ 217,609
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		$ 426,284	$ 406,340
Common Equity Tier 1 Capital to Risk Weighted Assets		11.46%	11.20%
Common Equity Tier 1 Capital Required for Capital Adequacy		$ 167,327	$ 163,207
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]	$ 448,282	$ 428,338
Tier 1 Leverage Capital to Average Assets	[1]	8.76%	8.89%
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 204,811	$ 192,690
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		$ 473,515	$ 453,033
Total Capital to Risk-Weighted Assets		12.74%	12.49%
Total Capital for Capital Adequacy Purposes		$ 297,426	$ 290,128
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		8.00%	8.00%
Total Capital To Be Well Capitalized		$ 371,783	$ 362,660
Total Capital To Be Well Capitalized to Risk Weighted-Assets		10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 445,815	$ 425,672
Tier 1 Capital to Risk Weighted-Assets		11.99%	11.74%
Tier 1 Capital Required For Capital Adequacy Purposes		$ 223,070	$ 217,596
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets		6.00%	6.00%
Tier 1 Capital Required To Be Well Capitalized		$ 297,426	$ 290,128
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		$ 445,815	$ 425,672
Common Equity Tier 1 Capital to Risk Weighted Assets		11.99%	11.74%
Common Equity Tier 1 Capital Required for Capital Adequacy		$ 167,302	$ 163,197
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		$ 241,659	$ 235,729
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]	$ 445,815	$ 425,672
Tier 1 Leverage Capital to Average Assets	[1]	8.71%	8.84%
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 204,724	$ 192,652
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]	$ 255,906	$ 240,815
Tier 1 Leverage Capital Required To Be Well Capitalized to Average Assets	[1]	5.00%	5.00%

[1] Leverage ratio.