Investment Securities, Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 187,815	$ 203,421
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,014	5,992
Held-to-Maturity:
Less than 12 Months, Fair Value	0	766
Less than 12 Months, Unrealized Losses	0	2
12 Months or More, Fair Value	21,784	21,742
12 Months or More, Unrealized Losses	240	779
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	730	19,389
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	56
U.S. Treasury notes [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,257	2,235
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	19	43
Held-to-Maturity:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
U.S. Agency notes [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	74,450	73,351
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,231	2,361
Held-to-Maturity:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	4,988
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	7
U.S. Agency mortgage-backed securities [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	54,245	55,217
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,161	1,981
Held-to-Maturity:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	111	137
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Non-taxable Municipal securities [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	43,862	58,211
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	515	1,373
Held-to-Maturity:
Less than 12 Months, Fair Value	0	366
Less than 12 Months, Unrealized Losses	0	1
12 Months or More, Fair Value	18,537	18,588
12 Months or More, Unrealized Losses	187	634
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	619	14,264
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	49
Taxable Municipal securities [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	13,001	14,407
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	88	234
Held-to-Maturity:
Less than 12 Months, Fair Value	0	400
Less than 12 Months, Unrealized Losses	0	1
12 Months or More, Fair Value	3,247	3,154
12 Months or More, Unrealized Losses	53	145
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 0