Investment Securities Schedule of Held to Maturity Securities (Details) $ in Thousands	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $343,751 at December 31, 2016, and $325,930 at December 31, 2015)	$ 345,427	$ 320,611
Held-To-Maturity Securities, at Fair Value	343,751	325,930
Gross Unrealized Gains	2,316	5,487
Gross Unrealized Losses	3,992	168
Held-To-Maturity Securities, Pledged as Collateral, at Fair Value	321,202	299,767
Maturities of Debt Securities, at Amortized Cost:
Within One Year	33,456
From 1 - 5 Years	147,782
From 5 - 10 Years	160,426
Over 10 Years	3,763
Maturities of Debt Securities, at Fair Value:
Within One Year	32,505
From 1 - 5 Years	149,250
From 5 - 10 Years	157,235
Over 10 Years	4,761
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	120,561	8,302
12 Months or Longer	12,363	15,918
Total	$ 132,924	$ 24,220
Number of Securities in a Continuous Loss Position	360	62
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 3,298	$ 104
12 Months or Longer	694	64
Total	3,992	168
State and Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $343,751 at December 31, 2016, and $325,930 at December 31, 2015)	268,892	226,053
Held-To-Maturity Securities, at Fair Value	267,127	230,621
Gross Unrealized Gains	2,058	4,619
Gross Unrealized Losses	3,823	51
Maturities of Debt Securities, at Amortized Cost:
Within One Year	32,456
From 1 - 5 Years	86,070
From 5 - 10 Years	146,603
Over 10 Years	3,763
Maturities of Debt Securities, at Fair Value:
Within One Year	32,505
From 1 - 5 Years	87,486
From 5 - 10 Years	143,375
Over 10 Years	3,761
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	107,255	2,302
12 Months or Longer	12,363	11,764
Total	$ 119,618	$ 14,066
Number of Securities in a Continuous Loss Position	347	54
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 3,129	$ 11
12 Months or Longer	694	40
Total	3,823	51
Collateralized Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $343,751 at December 31, 2016, and $325,930 at December 31, 2015)	75,535	93,558
Held-To-Maturity Securities, at Fair Value	75,624	94,309
Gross Unrealized Gains	258	868
Gross Unrealized Losses	169	117
Maturities of Debt Securities, at Amortized Cost:
Within One Year	0
From 1 - 5 Years	61,712
From 5 - 10 Years	13,823
Over 10 Years	0
Maturities of Debt Securities, at Fair Value:
Within One Year	0
From 1 - 5 Years	61,764
From 5 - 10 Years	13,860
Over 10 Years	0
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	13,306	6,000
12 Months or Longer	0	4,154
Total	$ 13,306	$ 10,154
Number of Securities in a Continuous Loss Position	13	8
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 169	$ 93
12 Months or Longer	0	24
Total	169	117
Corporate and Other Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $343,751 at December 31, 2016, and $325,930 at December 31, 2015)	1,000	1,000
Held-To-Maturity Securities, at Fair Value	1,000	1,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Maturities of Debt Securities, at Amortized Cost:
Within One Year	1,000
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	1,000
Securities in a Continuous Loss Position, at Fair Value:
Less than 12 Months	0	0
12 Months or Longer	0	0
Total	$ 0	$ 0
Number of Securities in a Continuous Loss Position	0	0
Unrealized Losses on Securities in a Continuous Loss Position:
Less than 12 Months	$ 0	$ 0
12 Months or Longer	0	0
Total	0	0
Collateralized Mortgage Backed Securities [Member] | Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $343,751 at December 31, 2016, and $325,930 at December 31, 2015)	3,206	3,802
Collateralized Mortgage Backed Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity (Approximate Fair Value of $343,751 at December 31, 2016, and $325,930 at December 31, 2015)	72,329	89,756
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Backed Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Fair Value	72,402	90,457
Fair Value, Measurements, Recurring [Member] | Agency Securities [Member] | Collateralized Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-To-Maturity Securities, at Fair Value	$ 3,222	$ 3,852