Investment Securities, Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 115,498	$ 110,869
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,772	3,085
Held-to-Maturity:
Less than 12 Months, Fair Value	17,628	9,824
Less than 12 Months, Unrealized Losses	619	133
12 Months or More, Fair Value	6,690	6,747
12 Months or More, Unrealized Losses	246	189
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	121,764	107,759
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,334	939
U.S. Treasury notes [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Held-to-Maturity:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	2,202	2,259
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	78	24
U.S. Agency notes [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	48,932	44,560
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,359	1,289
Held-to-Maturity:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	31,616	33,651
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	867	344
U.S. Agency mortgage-backed securities [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	39,827	41,080
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,088	1,085
Held-to-Maturity:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	19,555	24,433
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	483	142
Non-taxable Municipal securities [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	23,525	24,197
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,242	703
Held-to-Maturity:
Less than 12 Months, Fair Value	17,229	9,824
Less than 12 Months, Unrealized Losses	618	133
12 Months or More, Fair Value	3,539	3,542
12 Months or More, Unrealized Losses	97	94
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	54,493	36,348
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	691	315
Taxable Municipal securities [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	3,214	1,032
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	83	8
Held-to-Maturity:
Less than 12 Months, Fair Value	399	0
Less than 12 Months, Unrealized Losses	1	0
12 Months or More, Fair Value	3,151	3,205
12 Months or More, Unrealized Losses	149	95
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	13,898	11,068
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 215	$ 114