Securities Held to Maturity (Summary of Volume of State and Political Subdivision Securities Held in Portfolio) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	$ 98,528	$ 99,914
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	2,336	3,271
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	71	28
Debt Securities, Held-to-maturity, Fair Value	100,793	$ 103,157
TEXAS
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	15,475
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	439
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	7
Debt Securities, Held-to-maturity, Fair Value	15,907
CALIFORNIA
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	9,927
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	262
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	4
Debt Securities, Held-to-maturity, Fair Value	10,185
PENNSYLVANIA
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	8,672
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	253
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0
Debt Securities, Held-to-maturity, Fair Value	8,925
FLORIDA
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	7,628
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	139
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0
Debt Securities, Held-to-maturity, Fair Value	7,767
MICHIGAN
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	7,065
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	130
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	24
Debt Securities, Held-to-maturity, Fair Value	$ 7,171