Investment Securities Held to Maturity (Details) $ in Thousands	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	$ 324,116	$ 302,024	$ 297,437	$ 297,437
Held-to-Maturity Securities, at Fair Value	328,361	308,566		304,259
Gross Unrealized Gains	4,938	6,705		7,006
Gross Unrealized Losses	692	163		184
Held-To-Maturity Securities, Pledged as Collateral	300,040	282,640		296,437
Maturities of Debt Securities at Amortized Cost
Within One Year	19,962
From 1 - 5 Years	163,118
From 5 - 10 Years	125,269
Over 10 Years	15,767
Maturities of Debt Securities, at Fair Value
Within One Year	19,972
From 1 - 5 Years	165,533
From 5 - 10 Years	127,110
Over 10 Years	15,747
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	0	6,724		12,258
12 Months or Longer	48,715	16,033		15,033
Total	$ 48,715	$ 22,757		$ 27,291
Number of Securities in a Continuous Loss Position, in number of securities	158	75		67
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	$ 0	$ 25		$ 56
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	692	138		128
Total	692	163		184
State and Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	219,878	188,472		174,888
Held-to-Maturity Securities, at Fair Value	223,031	193,252		180,211
Gross Unrealized Gains	3,737	4,935		5,473
Gross Unrealized Losses	583	155		150
Maturities of Debt Securities at Amortized Cost
Within One Year	19,962
From 1 - 5 Years	93,785
From 5 - 10 Years	91,364
Over 10 Years	14,767
Maturities of Debt Securities, at Fair Value
Within One Year	19,972
From 1 - 5 Years	95,510
From 5 - 10 Years	92,802
Over 10 Years	14,747
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	0	2,143		2,697
12 Months or Longer	44,748	16,033		13,839
Total	$ 44,748	$ 18,176		$ 16,536
Number of Securities in a Continuous Loss Position, in number of securities	157	74		63
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	$ 0	$ 17		$ 29
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	583	138		121
Total	583	155		150
Mortgage-Backed Securities - Residential [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	103,238	112,552		121,549
Held-to-Maturity Securities, at Fair Value	104,330	114,314		123,048
Gross Unrealized Gains	1,201	1,770		1,533
Gross Unrealized Losses	109	8		34
Maturities of Debt Securities at Amortized Cost
Within One Year	0
From 1 - 5 Years	69,333
From 5 - 10 Years	33,905
Over 10 Years	0
Maturities of Debt Securities, at Fair Value
Within One Year	0
From 1 - 5 Years	70,023
From 5 - 10 Years	34,308
Over 10 Years	0
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	0	4,581		9,561
12 Months or Longer	3,967	0		1,194
Total	$ 3,967	$ 4,581		$ 10,755
Number of Securities in a Continuous Loss Position, in number of securities	1	1		4
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	$ 0	$ 8		$ 27
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	109	0		7
Total	109	8		34
Mortgage-Backed Securities - Residential [Member] | U.S. Government Agency Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	28,800	4,400		4,600
Held-to-Maturity Securities, at Fair Value	29,000	4,500		4,700
Mortgage-Backed Securities - Residential [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	74,500	108,100		116,900
Held-to-Maturity Securities, at Fair Value	75,400	109,800		118,300
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