Fair Value Measurements (Estimated Fair Values of Financial Assets and Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financial assets, Estimated Fair Value
Investment securities held to maturity	$ 247,835	$ 65,828
Fair Value, Inputs, Level 1 [Member] | Carrying Amount [Member]
Financial assets, Estimated Fair Value
Cash and cash equivalents	310,852	186,917
Fair Value, Inputs, Level 1 [Member] | Estimated Fair Value [Member]
Financial assets, Estimated Fair Value
Cash and cash equivalents	310,852	186,917
Fair Value, Inputs, Level 2 [Member] | Carrying Amount [Member]
Financial assets, Estimated Fair Value
Investment securities held to maturity	250,501	65,706
Restricted securities	3,189	3,626
Cash surrender value on life insurance	41,949	31,018
Financial liabilities, Estimated Fair Value
Noninterest-bearing demand	554,902	509,091
Checking plus interest	515,796	446,243
Money market	443,270	292,974
Savings	220,346	177,524
Club	1,490	392
Certificates of deposit, $100,000 or more	140,390	129,623
Other time	141,871	144,858
Securities sold under retail repurchase agreement	3,501	1,050
Subordinated debt	24,521	24,429
Fair Value, Inputs, Level 2 [Member] | Estimated Fair Value [Member]
Financial assets, Estimated Fair Value
Investment securities held to maturity	247,835	65,828
Restricted securities	3,189	3,626
Cash surrender value on life insurance	41,949	31,018
Financial liabilities, Estimated Fair Value
Noninterest-bearing demand	554,902	509,091
Checking plus interest	515,796	446,243
Money market	443,270	292,974
Savings	220,346	177,524
Club	1,490	392
Certificates of deposit, $100,000 or more	141,610	131,271
Other time	142,450	146,137
Securities sold under retail repurchase agreement	3,501	1,050
Subordinated debt	26,903	25,745
Fair Value, Inputs, Level 3 [Member] | Carrying Amount [Member]
Financial assets, Estimated Fair Value
Loans, net	1,479,372	1,440,368
Fair Value, Inputs, Level 3 [Member] | Estimated Fair Value [Member]
Financial assets, Estimated Fair Value
Loans, net	$ 1,475,793	$ 1,436,292