Securities Held to Maturity (Summary of Volume of State and Political Subdivision Securities Held in Portfolio) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	$ 99,457	$ 99,914
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	1,284	3,271
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	387	28
Debt Securities, Held-to-maturity, Fair Value	100,354	$ 103,157
TEXAS
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	15,622
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	342
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	15
Debt Securities, Held-to-maturity, Fair Value	15,949
CALIFORNIA
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	10,030
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	144
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	30
Debt Securities, Held-to-maturity, Fair Value	10,144
PENNSYLVANIA
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	8,748
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	9
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	18
Debt Securities, Held-to-maturity, Fair Value	8,739
FLORIDA
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	7,692
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	77
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0
Debt Securities, Held-to-maturity, Fair Value	7,769
MICHIGAN
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	7,129
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	42
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	52
Debt Securities, Held-to-maturity, Fair Value	$ 7,119