Investment Securities Held to Maturity (Details) $ in Thousands	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	$ 279,400	$ 283,476	$ 330,124
Held-To-Maturity Securities, at Fair Value	280,414	280,338	324,937
Gross Unrealized Gains	1,792	486	646
Gross Unrealized Losses	778	3,624	5,832
Maturities of Debt Securities, at Amortized Cost:
Within One Year	25,205
From 1 - 5 Years	139,046
From 5 - 10 Years	112,788
Over 10 Years	2,361
Maturities of Debt Securities, at Fair Value:
Within One Year	25,244
From 1 - 5 Years	139,428
From 5 - 10 Years	113,343
Over 10 Years	2,399
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	0	65,402	154,771
12 Months or Longer	97,471	124,617	68,269
Total	$ 97,471	$ 190,019	$ 223,040
Number of Securities in a Continuous Loss Position	222	458	542
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 0	$ 618	$ 2,748
12 Months or Longer	778	3,006	3,084
Total	778	3,624	5,832
Equity Securities	1,850	1,774	1,579
State and Municipal Obligations
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	234,454	235,782	272,938
Held-To-Maturity Securities, at Fair Value	235,576	233,359	268,604
Gross Unrealized Gains	1,695	486	646
Gross Unrealized Losses	573	2,909	4,979
Maturities of Debt Securities, at Amortized Cost:
Within One Year	25,205
From 1 - 5 Years	94,100
From 5 - 10 Years	112,788
Over 10 Years	2,361
Maturities of Debt Securities, at Fair Value:
Within One Year	25,244
From 1 - 5 Years	94,590
From 5 - 10 Years	113,343
Over 10 Years	2,399
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	0	32,093	101,695
12 Months or Longer	71,450	110,947	65,012
Total	$ 71,450	$ 143,040	$ 166,707
Number of Securities in a Continuous Loss Position	193	411	495
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 0	$ 162	$ 1,981
12 Months or Longer	573	2,747	2,998
Total	573	2,909	4,979
Mortgage-Backed Securities - Residential
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	44,946	47,694	57,186
Held-To-Maturity Securities, at Fair Value	44,838	46,979	56,333
Gross Unrealized Gains	97	0	0
Gross Unrealized Losses	205	715	853
Maturities of Debt Securities, at Amortized Cost:
Within One Year	0
From 1 - 5 Years	44,946
From 5 - 10 Years	0
Over 10 Years	0
Maturities of Debt Securities, at Fair Value:
Within One Year	0
From 1 - 5 Years	44,838
From 5 - 10 Years	0
Over 10 Years	0
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	0	33,309	53,076
12 Months or Longer	26,021	13,670	3,257
Total	$ 26,021	$ 46,979	$ 56,333
Number of Securities in a Continuous Loss Position	29	47	47
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 0	$ 456	$ 767
12 Months or Longer	205	259	86
Total	205	715	853
US Government Agencies Debt Securities | Mortgage-Backed Securities - Residential
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	2,069	2,180	2,530
US Government-sponsored Enterprises Debt Securities | Mortgage-Backed Securities - Residential
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	42,877	45,514	54,656
Collateral Pledged
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, Pledged as Collateral	265,465	266,341	307,273
Fair Value, Measurements, Recurring
Unrealized Losses on Securities in a Continuous Loss Position:
Equity Securities	1,850	1,774	1,579
Fair Value, Measurements, Recurring | US Government Agencies Debt Securities | Mortgage-Backed Securities - Residential
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Fair Value	2,012	2,143	2,483
Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities | Mortgage-Backed Securities - Residential
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Fair Value	$ 42,826	$ 44,836	$ 53,850