Investment Securities Held to Maturity (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	$ 273,626	$ 239,803	$ 244,949
Held-to-Maturity Securities, at Fair Value	278,390	248,252	254,936
Gross Unrealized Gains	5,332	8,512	9,990
Gross Unrealized Losses	568	63	3
Held-To-Maturity Securities, Pledged as Collateral	272,626	238,803	243,949
Maturities of Debt Securities at Amortized Cost
Within One Year	45,615
From 1 - 5 Years	125,236
From 5 - 10 Years	98,230
Over 10 Years	4,545
Maturities of Debt Securities, at Fair Value
Within One Year	45,665
From 1 - 5 Years	127,161
From 5 - 10 Years	100,907
Over 10 Years	4,657
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	57,528	21,583	3,165
12 Months or Longer	171	503	0
Total	57,699	22,086	3,165
Number of Securities in a Continuous Loss Position, in number of securities	110	61	9
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	565	62	3
12 Months or Longer	2	1	0
Total	567	63	3
State and Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	194,065	183,373	179,412
Held-to-Maturity Securities, at Fair Value	198,548	191,196	188,127
Gross Unrealized Gains	5,018	7,886	8,718
Gross Unrealized Losses	535	63	3
Maturities of Debt Securities at Amortized Cost
Within One Year	45,615
From 1 - 5 Years	80,848
From 5 - 10 Years	64,057
Over 10 Years	3,545
Maturities of Debt Securities, at Fair Value
Within One Year	45,665
From 1 - 5 Years	82,492
From 5 - 10 Years	66,734
Over 10 Years	3,657
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	27,814	21,583	3,165
12 Months or Longer	171	503	0
Total	27,985	22,086	3,165
Number of Securities in a Continuous Loss Position, in number of securities	97	61	9
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	532	62	3
12 Months or Longer	2	1	0
Total	534	63	3
Mortgage-Backed Securities - Residential [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	78,561	55,430	64,537
Held-to-Maturity Securities, at Fair Value	78,842	56,056	65,809
Gross Unrealized Gains	314	626	1,272
Gross Unrealized Losses	33	0	0
Maturities of Debt Securities at Amortized Cost
Within One Year	0
From 1 - 5 Years	44,388
From 5 - 10 Years	34,173
Over 10 Years	0
Maturities of Debt Securities, at Fair Value
Within One Year	0
From 1 - 5 Years	44,669
From 5 - 10 Years	34,173
Over 10 Years	0
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	29,714	0	0
12 Months or Longer	0	0	0
Total	29,714	0	0
Number of Securities in a Continuous Loss Position, in number of securities	13	0	0
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	33	0	0
12 Months or Longer	0	0	0
Total	33	0	0
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
12 Months or Longer	0	0	0
Total	0	0	0
Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	5,000
Held-to-Maturity Securities, at Fair Value	4,900
US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-Maturity	73,600		64,500
Held-to-Maturity Securities, at Fair Value	$ 73,900		$ 65,800