Investment Securities Held to Maturity (Details) $ in Thousands	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Equity Securities	$ 1,916	$ 0	$ 0
Held-To-Maturity Securities, at Amortized Cost	289,952	335,907	341,526
Held-To-Maturity Securities, at Fair Value	282,719	335,901	343,899
Gross Unrealized Gains	261	1,960	3,715
Gross Unrealized Losses	7,494	1,966	1,342
Maturities of Debt Securities, at Amortized Cost:
Within One Year	19,381
From 1 - 5 Years	141,123
From 5 - 10 Years	126,823
Over 10 Years	2,625
Maturities of Debt Securities, at Fair Value:
Within One Year	19,396
From 1 - 5 Years	138,887
From 5 - 10 Years	121,830
Over 10 Years	2,606
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	142,319	69,412	81,782
12 Months or Longer	89,165	68,409	13,331
Total	$ 231,484	$ 137,821	$ 95,113
Number of Securities in a Continuous Loss Position	582	366	259
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 2,746	$ 498	$ 1,045
12 Months or Longer	4,748	1,468	297
Total	7,494	1,966	1,342
State and Municipal Obligations
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	239,367	275,530	277,738
Held-To-Maturity Securities, at Fair Value	233,557	275,353	279,384
Gross Unrealized Gains	261	1,691	2,977
Gross Unrealized Losses	6,071	1,868	1,331
Maturities of Debt Securities, at Amortized Cost:
Within One Year	19,381
From 1 - 5 Years	93,084
From 5 - 10 Years	124,277
Over 10 Years	2,625
Maturities of Debt Securities, at Fair Value:
Within One Year	19,396
From 1 - 5 Years	92,199
From 5 - 10 Years	119,356
Over 10 Years	2,606
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	95,944	55,648	78,238
12 Months or Longer	86,378	65,152	13,331
Total	$ 182,322	$ 120,800	$ 91,569
Number of Securities in a Continuous Loss Position	535	352	252
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 1,443	$ 442	$ 1,034
12 Months or Longer	4,628	1,425	297
Total	6,071	1,867	1,331
Mortgage-Backed Securities - Residential
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	50,585	60,377	63,788
Held-To-Maturity Securities, at Fair Value	49,162	60,548	64,515
Gross Unrealized Gains	0	269	738
Gross Unrealized Losses	1,423	98	11
Maturities of Debt Securities, at Amortized Cost:
Within One Year	0
From 1 - 5 Years	48,039
From 5 - 10 Years	2,546
Over 10 Years	0
Maturities of Debt Securities, at Fair Value:
Within One Year	0
From 1 - 5 Years	46,688
From 5 - 10 Years	2,474
Over 10 Years	0
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	46,375	13,764	3,544
12 Months or Longer	2,787	3,257	0
Total	$ 49,162	$ 17,021	$ 3,544
Number of Securities in a Continuous Loss Position	47	14	7
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 1,303	$ 56	$ 11
12 Months or Longer	120	43	0
Total	1,423	99	11
Corporate and Other Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	0	0	0
Held-To-Maturity Securities, at Fair Value	0	0	0
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	0	0	0
Maturities of Debt Securities, at Amortized Cost:
Within One Year	0
From 1 - 5 Years	0
From 5 - 10 Years	0
Over 10 Years	0
Maturities of Debt Securities, at Fair Value:
Within One Year	0
From 1 - 5 Years	0
From 5 - 10 Years	0
Over 10 Years	0
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	0	0	0
12 Months or Longer	0	0	0
Total	$ 0	$ 0	$ 0
Number of Securities in a Continuous Loss Position	0	0	0
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 0	$ 0	$ 0
12 Months or Longer	0	0	0
Total	0	0	0
US Government Agencies Debt Securities | Mortgage-Backed Securities - Residential
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Amortized Cost	3,147	2,680	2,792
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	47,438	57,697	60,996
Collateral Pledged
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, Pledged as Collateral	268,229	318,622	325,096
Fair Value, Measurements, Recurring
Schedule of Held-to-maturity Securities [Line Items]
Equity Securities	1,916
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	2,222	2,661	2,799
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	$ 46,940	$ 57,887	$ 61,716