Investment Securities Gross Unrealized Losses and Fair Values of Investment Securities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012 securities	Dec. 31, 2011 securities
Available-for-Sale:
Available-for-Sale, Less Than 12 Months Fair Value	$ 108,110	$ 333,344
Available-for-Sale, Less Than 12 Months Gross Unrealized Losses	(178)	(686)
Available-for-Sale, 12 Months or More Fair Value	160	177
Available-for-Sale, 12 Months or More Gross Unrealized Losses	(2)	(6)
Available-for-Sale, Total Fair Value	108,270	333,521
Available-for-Sale, Total Gross Unrealized Losses	(180)	(692)
Available-for-Sale and Held-to-Maturity:
Investment Securities in an Unrealized Loss Position (Number of Securities)	29	24
Obligations of U.S. government agencies
Available-for-Sale:
Available-for-Sale, Less Than 12 Months Fair Value	64,982	287,404
Available-for-Sale, Less Than 12 Months Gross Unrealized Losses	(71)	(662)
Available-for-Sale, 12 Months or More Fair Value	0	0
Available-for-Sale, 12 Months or More Gross Unrealized Losses	0	0
Available-for-Sale, Total Fair Value	64,982	287,404
Available-for-Sale, Total Gross Unrealized Losses	(71)	(662)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations
Available-for-Sale:
Available-for-Sale, Less Than 12 Months Fair Value	42,902	45,694
Available-for-Sale, Less Than 12 Months Gross Unrealized Losses	(106)	(14)
Available-for-Sale, 12 Months or More Fair Value	0	0
Available-for-Sale, 12 Months or More Gross Unrealized Losses	0	0
Available-for-Sale, Total Fair Value	42,902	45,694
Available-for-Sale, Total Gross Unrealized Losses	(106)	(14)
Private mortgage-backed securities
Available-for-Sale:
Available-for-Sale, Less Than 12 Months Fair Value	226	246
Available-for-Sale, Less Than 12 Months Gross Unrealized Losses	(1)	(10)
Available-for-Sale, 12 Months or More Fair Value	160	177
Available-for-Sale, 12 Months or More Gross Unrealized Losses	(2)	(6)
Available-for-Sale, Total Fair Value	386	423
Available-for-Sale, Total Gross Unrealized Losses	(3)	(16)
State, county and municipal securities
Held-to-Maturity:
Held-to-Maturity, Less than 12 Months Fair Value	7,451	0
Held-to-Maturity, Less than 12 Months Gross Unrealized Losses	(80)	0
Held-to-Maturity, 12 Months or More Fair Value	721	773
Held-to-Maturity, 12 Months or More Gross Unrealized Losses	(17)	(17)
Held-to-Maturity, Total Fair Value	8,172	773
Held-to-Maturity, Total Gross Unrealized Losses	$ (97)	$ (17)

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