Investment Securities Held to Maturity (Details) $ in Thousands	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	$ 338,238	$ 320,611	$ 317,480
Held-to-Maturity Securities, at Fair Value	347,441	325,930	324,009
Gross Unrealized Gains	9,273	5,487	6,614
Gross Unrealized Losses	70	168	85
Held-To-Maturity Securities, Pledged as Collateral	320,774	299,767	296,921
Maturities of Debt Securities at Amortized Cost
Within One Year	35,911
From 1 - 5 Years	159,886
From 5 - 10 Years	137,452
Over 10 Years	4,989
Maturities of Debt Securities, at Fair Value
Within One Year	35,966
From 1 - 5 Years	164,659
From 5 - 10 Years	141,681
Over 10 Years	5,135
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	11,891	8,302	0
12 Months or Longer	1,172	15,918	14,896
Total	$ 13,063	$ 24,220	$ 14,896
Number of Securities in a Continuous Loss Position, in number of securities	3	62	51
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	$ 68	$ 104	$ 0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2	64	85
Total	70	168	85
State and Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	257,255	226,053	218,502
Held-to-Maturity Securities, at Fair Value	263,897	230,621	223,050
Gross Unrealized Gains	6,712	4,619	4,633
Gross Unrealized Losses	70	51	85
Maturities of Debt Securities at Amortized Cost
Within One Year	35,911
From 1 - 5 Years	87,464
From 5 - 10 Years	129,891
Over 10 Years	3,989
Maturities of Debt Securities, at Fair Value
Within One Year	35,966
From 1 - 5 Years	89,979
From 5 - 10 Years	133,817
Over 10 Years	4,135
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	11,891	2,302	0
12 Months or Longer	1,172	11,764	14,896
Total	$ 13,063	$ 14,066	$ 14,896
Number of Securities in a Continuous Loss Position, in number of securities	3	54	51
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	$ 68	$ 11	$ 0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2	40	85
Total	70	51	85
Mortgage-Backed Securities - Residential [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	79,983	93,558	97,978
Held-to-Maturity Securities, at Fair Value	82,544	94,309	99,959
Gross Unrealized Gains	2,561	868	1,981
Gross Unrealized Losses	0	117	0
Maturities of Debt Securities at Amortized Cost
Within One Year	0
From 1 - 5 Years	72,422
From 5 - 10 Years	7,561
Over 10 Years	0
Maturities of Debt Securities, at Fair Value
Within One Year	0
From 1 - 5 Years	74,680
From 5 - 10 Years	7,864
Over 10 Years	0
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	0	6,000	0
12 Months or Longer	0	4,154	0
Total	$ 0	$ 10,154	$ 0
Number of Securities in a Continuous Loss Position, in number of securities	0	8	0
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	$ 0	$ 93	$ 0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	24	0
Total	0	117	0
Mortgage-Backed Securities - Residential [Member] | U.S. Government Agency Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	3,497	3,800	27,800
Held-to-Maturity Securities, at Fair Value	3,622	3,940	28,400
Mortgage-Backed Securities - Residential [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	76,486	89,758	70,200
Held-to-Maturity Securities, at Fair Value	78,922	90,469	71,500
Corporate and Other Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	1,000	1,000	1,000
Held-to-Maturity Securities, at Fair Value	1,000	1,000	1,000
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	1,000
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	0
12 Months or Longer	0	0	0
Total	$ 0	$ 0	$ 0
Number of Securities in a Continuous Loss Position, in number of securities	0	0	0
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	$ 0	$ 0	$ 0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0	0
Total	$ 0	$ 0	$ 0