Investment Securities Held to Maturity (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity	$ 244,949	$ 150,688	$ 146,416
Held-to-Maturity Securities, at Fair Value	254,936	159,059	153,131
Gross Unrealized Gains	9,990	8,378	6,715
Gross Unrealized Losses	3	7	0
Held-To-Maturity Securities, Pledged as Collateral	244,949	150,688	146,416
Maturities of Debt Securities at Amortized Cost
Within One Year	31,578
From 1 - 5 Years	150,946
From 5 - 10 Years	56,959
Over 10 Years	5,466
Maturities of Debt Securities, at Fair Value
Within One Year	31,664
From 1 - 5 Years	154,933
From 5 - 10 Years	62,578
Over 10 Years	5,761
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	3,165	510	0
12 Months or Longer	0	0	0
Total	3,165	510	0
Number of Securities in a Continuous Loss Position, in number of securities	9	1	0
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	3	7	0
12 Months or Longer	0	0	0
Total	3	7	0
State and Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity	179,412	149,688	145,416
Held-to-Maturity Securities, at Fair Value	188,127	158,059	152,131
Gross Unrealized Gains	8,718	8,378	6,715
Gross Unrealized Losses	3	7	0
Maturities of Debt Securities at Amortized Cost
Within One Year	31,578
From 1 - 5 Years	86,409
From 5 - 10 Years	56,959
Over 10 Years	4,466
Maturities of Debt Securities, at Fair Value
Within One Year	31,664
From 1 - 5 Years	89,124
From 5 - 10 Years	62,578
Over 10 Years	4,761
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	3,165	510	0
12 Months or Longer	0	0	0
Total	3,165	510	0
Number of Securities in a Continuous Loss Position, in number of securities	9	1	0
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	3	7	0
12 Months or Longer	0	0	0
Total	3	7	0
Mortgage-Backed Securities - Residential [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity	64,537	0	0
Held-to-Maturity Securities, at Fair Value	65,809	0	0
Gross Unrealized Gains	1,272	0	0
Gross Unrealized Losses	0	0	0
Maturities of Debt Securities at Amortized Cost
Within One Year	0
From 1 - 5 Years	64,537
From 5 - 10 Years	0
Over 10 Years	0
Maturities of Debt Securities, at Fair Value
Within One Year	0
From 1 - 5 Years	65,809
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, 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
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