Shareholders' Equity (Regulatory Captial Requirements) (Details) $ in Thousands		Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Corporation [Member]
Total Capital (to Risk-Weighted Assets):
Total Capital		$ 569,424	$ 539,496
Total Capital to Risk-Weighted Assets		0.1383	0.1351
Total Capital for Capital Adequacy Purposes		$ 329,407	$ 319,532
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		0.0800	0.0800
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 535,552	$ 503,791
Tier 1 Capital to Risk Weighted-Assets		0.1301	0.1261
Tier 1 Capital Required For Capital Adequacy Purposes		$ 247,055	$ 239,649
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets		0.0600	0.0600
Common Equity Tier 1 Capital [Abstract]
Common Equity Tier 1 Capital		$ 513,553	$ 481,792
Common Equity Tier 1 Capital to Risk-Weighted Assets		0.1247	0.1206
Common Equity Tier 1 Capital Required for Capital Adequacy		$ 185,291	$ 179,737
Common Equity Tier 1 Capital for Capital Adequacy Purposes to Risk-Weighted Assets		0.0450	0.0450
Tier 1 Capital (to Average Assets):
Tier 1 Leverage Capital	[1]	$ 535,552	$ 503,791
Tier 1 Leverage Capital to Average Assets	[1]	0.0912	0.0895
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 234,803	$ 225,209
Tier 1 Leverage Capital Required for Capital Adequacy Purposes to Average Assets	[1]	0.0400	0.0400
Bank [Member]
Total Capital (to Risk-Weighted Assets):
Total Capital		$ 559,605	$ 534,288
Total Capital to Risk-Weighted Assets		0.1359	0.1338
Total Capital for Capital Adequacy Purposes		$ 329,378	$ 319,503
Total Capital for Capital Adequacy Purposes to Risk-Weighted Assets		0.0800	0.0800
Total Capital To Be Well Capitalized		$ 411,723	$ 399,379
Total Capital To Be Well Capitalized to Risk Weighted-Assets		0.1000	0.1000
Tier 1 Capital (to Risk-Weighted Assets):
Tier 1 Capital		$ 525,733	$ 498,583
Tier 1 Capital to Risk Weighted-Assets		0.1277	0.1248
Tier 1 Capital Required For Capital Adequacy Purposes		$ 247,034	$ 239,627
Tier 1 Capital Required for Capital Adequacy Purposes to Risk Weighted-Assets		0.0600	0.0600
Tier 1 Capital Required To Be Well Capitalized		$ 329,378	$ 319,503
Tier 1 Capital Required To Be Well Capitalized to Risk Weighted-Assets		0.0800	0.0800
Common Equity Tier 1 Capital [Abstract]
Common Equity Tier 1 Capital		$ 525,733	$ 498,583
Common Equity Tier 1 Capital to Risk-Weighted Assets		0.1277	0.1248
Common Equity Tier 1 Capital Required for Capital Adequacy		$ 185,275	$ 179,721
Common Equity Tier 1 Capital for Capital Adequacy Purposes to Risk-Weighted Assets		0.0450	0.0450
Common Equity Tier 1 Capital To Be Well Capitalized		$ 267,620	$ 259,596
Common Equity Tier 1 Capital To Be Well Capitalized to Risk-Weighted Assets		0.0650	0.0650
Tier 1 Capital (to Average Assets):
Tier 1 Leverage Capital	[1]	$ 525,733	$ 498,583
Tier 1 Leverage Capital to Average Assets	[1]	0.0896	0.0886
Tier 1 Leverage Capital Required for Capital Adequacy Purposes	[1]	$ 234,722	$ 225,126
Tier 1 Leverage Capital Required for Capital Adequacy Purposes to Average Assets	[1]	0.0400	0.0400
Tier 1 Leverage Capital Required To Be Well Capitalized	[1]	$ 293,403	$ 281,407
Tier 1 Leverage Capital Required To Be Well Capitalized to Average Assets	[1]	0.0500	0.0500

[1] Leverage ratio.