Fair Value (Carrying Amounts and Estimated Fair Values of Company's Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial Assets:
Loans, Net	$ 2,125,944	$ 1,975,147
FHLB Stock and Other Restricted Stock	13,048	13,048
Financial Liabilities:
Time Deposits	(387,885)	(378,181)
Short-term Borrowings	(133,499)	(137,554)
Long-term Debt	(141,717)	(120,560)
Reported Value Measurement
Financial Assets:
Cash and Short-term Investments	70,359	64,816
Loans, Net	2,119,152	1,974,074
FHLB Stock and Other Restricted Stock	13,048	13,048
Accrued Interest Receivable	13,258	11,413
Financial Liabilities:
Demand, Savings, and Money Market Deposits	(2,096,167)	(1,971,370)
Time Deposits	(387,885)	(378,181)
Short-term Borrowings	(133,499)	(137,554)
Long-term Debt	(141,717)	(120,560)
Accrued Interest Payable	(1,058)	(789)
Estimate of Fair Value Measurement
Financial Assets:
Cash and Short-term Investments	70,359	64,816
Loans, Net	2,120,154	1,980,523
Accrued Interest Receivable	13,258	11,413
Financial Liabilities:
Demand, Savings, and Money Market Deposits	(2,096,167)	(1,971,370)
Time Deposits	(388,640)	(378,000)
Short-term Borrowings	(133,499)	(137,554)
Long-term Debt	(140,418)	(120,502)
Accrued Interest Payable	(1,058)	(789)
Estimate of Fair Value Measurement | Level 1
Financial Assets:
Cash and Short-term Investments	58,233	48,467
Loans, Net	0	0
Accrued Interest Receivable	0	0
Financial Liabilities:
Demand, Savings, and Money Market Deposits	(2,096,167)	(1,971,370)
Time Deposits	0	0
Short-term Borrowings	0	0
Long-term Debt	0	0
Accrued Interest Payable	0	0
Estimate of Fair Value Measurement | Level 2
Financial Assets:
Cash and Short-term Investments	12,126	16,349
Loans, Net	0	0
Accrued Interest Receivable	3,574	3,289
Financial Liabilities:
Demand, Savings, and Money Market Deposits	0	0
Time Deposits	(388,640)	(378,000)
Short-term Borrowings	(133,499)	(137,554)
Long-term Debt	(129,366)	(109,709)
Accrued Interest Payable	(1,042)	(775)
Estimate of Fair Value Measurement | Level 3
Financial Assets:
Cash and Short-term Investments	0	0
Loans, Net	2,120,154	1,980,523
Accrued Interest Receivable	9,684	8,124
Financial Liabilities:
Demand, Savings, and Money Market Deposits	0	0
Time Deposits	0	0
Short-term Borrowings	0	0
Long-term Debt	(11,052)	(10,793)
Accrued Interest Payable	$ (16)	$ (14)