Investment Securities, Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 97,850	$ 203,421
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	899	5,992
Held-to-Maturity:
Less than 12 Months, Fair Value	72	766
Less than 12 Months, Unrealized Losses	0	2
12 Months or More, Fair Value	3,490	21,742
12 Months or More, Unrealized Losses	30	779
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	69	19,389
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	56
U.S. Treasury notes [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	2,235
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	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	39,413	73,351
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	292	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	32,554	55,217
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	441	1,981
Held-to-Maturity:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	69	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	21,330	58,211
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	155	1,373
Held-to-Maturity:
Less than 12 Months, Fair Value	72	366
Less than 12 Months, Unrealized Losses	0	1
12 Months or More, Fair Value	3,490	18,588
12 Months or More, Unrealized Losses	30	634
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	14,264
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	49
Taxable Municipal securities [Member]
Available-for-Sale:
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	4,553	14,407
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	11	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	0	3,154
12 Months or More, Unrealized Losses	0	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