Securities Continuous Unrealized Loss (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 119,892	$ 69,830
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	2,226	484
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	77,947	81,237
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	3,722	2,296
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	197,839	151,067
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	5,948	2,780
US Government and Government Agencies and Authorities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	29,050	14,381
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	264	99
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	19,981	20,353
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	1,135	805
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	49,031	34,734
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,399	904
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	77,341	53,440
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,710	363
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	48,048	50,729
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	2,161	1,276
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	125,389	104,169
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	3,871	1,639
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	13,501	2,009
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	252	22
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	9,918	10,155
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	426	215
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	23,419	12,164
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 678	$ 237