Investment Securities Schedule of Held to Maturity Securities (Details) $ in Thousands	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $280,338 at December 31, 2018, and $335,901 at December 31, 2017)	$ 283,476	$ 335,907
Held-To-Maturity Securities, at Fair Value	280,338	335,901
Gross Unrealized Gains	486	1,960
Gross Unrealized Losses	3,624	1,966
Held-To-Maturity Securities, Pledged as Collateral, at Fair Value	266,341	318,622
Maturities of Debt Securities, at Amortized Cost:
Within One Year	27,426
From 1 - 5 Years	141,189
From 5 - 10 Years	112,499
Over 10 Years	2,362
Maturities of Debt Securities, at Fair Value:
Within One Year	27,464
From 1 - 5 Years	140,109
From 5 - 10 Years	110,396
Over 10 Years	2,369
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	65,402	69,412
12 Months or Longer	124,617	68,409
Total	$ 190,019	$ 137,821
Number of Securities in a Continuous Loss Position	458	366
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 618	$ 498
12 Months or Longer	3,006	1,468
Total	3,624	1,966
State and Municipal Obligations
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $280,338 at December 31, 2018, and $335,901 at December 31, 2017)	235,782	275,530
Held-To-Maturity Securities, at Fair Value	233,359	275,353
Gross Unrealized Gains	486	1,691
Gross Unrealized Losses	2,909	1,868
Maturities of Debt Securities, at Amortized Cost:
Within One Year	27,426
From 1 - 5 Years	93,495
From 5 - 10 Years	112,499
Over 10 Years	2,362
Maturities of Debt Securities, at Fair Value:
Within One Year	27,464
From 1 - 5 Years	93,130
From 5 - 10 Years	110,396
Over 10 Years	2,369
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	32,093	55,648
12 Months or Longer	110,947	65,152
Total	$ 143,040	$ 120,800
Number of Securities in a Continuous Loss Position	411	352
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 162	$ 442
12 Months or Longer	2,747	1,425
Total	2,909	1,867
Collateralized Mortgage Backed Securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $280,338 at December 31, 2018, and $335,901 at December 31, 2017)	47,694	60,377
Held-To-Maturity Securities, at Fair Value	46,979	60,548
Gross Unrealized Gains	0	269
Gross Unrealized Losses	715	98
Maturities of Debt Securities, at Amortized Cost:
Within One Year	0
From 1 - 5 Years	47,694
From 5 - 10 Years	0
Over 10 Years	0
Maturities of Debt Securities, at Fair Value:
Within One Year	0
From 1 - 5 Years	46,979
From 5 - 10 Years	0
Over 10 Years	0
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	33,309	13,764
12 Months or Longer	13,670	3,257
Total	$ 46,979	$ 17,021
Number of Securities in a Continuous Loss Position	47	14
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 456	$ 56
12 Months or Longer	259	43
Total	715	99
Collateralized Mortgage Backed Securities | Agency Securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $280,338 at December 31, 2018, and $335,901 at December 31, 2017)	2,180	2,680
Collateralized Mortgage Backed Securities | US Government-sponsored Enterprises Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $280,338 at December 31, 2018, and $335,901 at December 31, 2017)	45,514	57,697
Collateralized Mortgage Backed Securities | Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Fair Value	44,836	57,887
Collateralized Mortgage Backed Securities | Fair Value, Measurements, Recurring | Agency Securities
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Fair Value	$ 2,143	$ 2,661