Investment Securities Held to Maturity (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity	$ 252,902	$ 150,688	$ 138,334
Held-to-Maturity Securities, at Fair Value	261,574	159,059	143,327
Gross Unrealized Gains	8,707	8,378	5,008
Gross Unrealized Losses	35	7	15
Held-To-Maturity Securities, Pledged as Collateral	252,902	150,688	138,334
Maturities of Debt Securities at Amortized Cost
Within One Year	35,450
From 1 - 5 Years	152,236
From 5 - 10 Years	59,047
Over 10 Years	6,169
Maturities of Debt Securities, at Fair Value
Within One Year	35,563
From 1 - 5 Years	155,040
From 5 - 10 Years	64,429
Over 10 Years	6,542
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	14,908	510	0
12 Months or Longer	0	0	1,561
Total	14,908	510	1,561
Number of Securities in a Continuous Loss Position, in number of securities	34	1	5
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	35	7	0
12 Months or Longer	0	0	15
Total	35	7	15
State and Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity	183,277	149,688	137,334
Held-to-Maturity Securities, at Fair Value	191,297	158,059	142,327
Gross Unrealized Gains	8,055	8,378	5,008
Gross Unrealized Losses	35	7	15
Maturities of Debt Securities at Amortized Cost
Within One Year	35,450
From 1 - 5 Years	83,611
From 5 - 10 Years	59,047
Over 10 Years	5,169
Maturities of Debt Securities, at Fair Value
Within One Year	35,563
From 1 - 5 Years	85,763
From 5 - 10 Years	64,429
Over 10 Years	5,542
Securities in a Continuous Loss Position, at Fair Value
Less than 12 Months	14,908	510	0
12 Months or Longer	0	0	1,561
Total	14,908	510	1,561
Number of Securities in a Continuous Loss Position, in number of securities	34,000	1,000	5,000
Unrealized Losses on Securities in a Continuous Loss Position
Less than 12 Months	35	7	0
12 Months or Longer	0	0	15
Total	35	7	15
Mortgage-Backed Securities - Residential [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity	68,625	0	0
Held-to-Maturity Securities, at Fair Value	69,277	0	0
Gross Unrealized Gains	652	0	0
Gross Unrealized Losses	0	0	0
Maturities of Debt Securities at Amortized Cost
Within One Year	0
From 1 - 5 Years	68,625
From 5 - 10 Years	0
Over 10 Years	0
Maturities of Debt Securities, at Fair Value
Within One Year	0
From 1 - 5 Years	69,277
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