Investment Securities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Amortized cost and fair value of investment securities held to maturity [Abstract]
Amortized Cost	$ 36,240	$ 40,357
Gross Unrealized Gains	1,550	1,376
Gross Unrealized Losses	0	(9)
Estimated Fair Value	37,790	41,724
Securities pledged as collateral for borrowings	8,417,000	6,432,000
Fair Value [Abstract]
Less than 12 Months, Fair Value	0	3,078
12 Months or More, Fair Value	0	0
Total, Fair Value	0	3,078
Unrealized Losses [Abstract]
Less than 12 Months, Unrealized Losses	0	(9)
12 Months or More, Unrealized Losses	0	0
Total, Unrealized Losses	0	(9)
Amortized Cost [Abstract]
Due in one year or less	5,018
Due from one year to five years	25,520
Due from five years to ten years	5,067
US Government sponsored Mortgage-backed securities	635
Total	36,240
Estimated Fair Value [Abstract]
Due in one year or less	5,046
Due from one year to five years	26,455
Due from five years to ten years	5,595
US Government sponsored Mortgage-backed securities	694
Total	37,790
US Treasury securities [Member]
Amortized cost and fair value of investment securities held to maturity [Abstract]
Amortized Cost	31,447	34,498
Gross Unrealized Gains	1,406	1,285
Gross Unrealized Losses	0	(5)
Estimated Fair Value	32,853	35,778
Number of securities in continuous unrealized loss position	0	2
Fair Value [Abstract]
Less than 12 Months, Fair Value	0	2,046
12 Months or More, Fair Value	0	0
Total, Fair Value	0	2,046
Unrealized Losses [Abstract]
Less than 12 Months, Unrealized Losses	0	(5)
12 Months or More, Unrealized Losses	0	0
Total, Unrealized Losses	0	(5)
US Agency Securities [Member]
Amortized cost and fair value of investment securities held to maturity [Abstract]
Amortized Cost	4,158	5,206
Gross Unrealized Gains	85	43
Gross Unrealized Losses	0	(4)
Estimated Fair Value	4,243	5,245
Number of securities in continuous unrealized loss position	0	1
Fair Value [Abstract]
Less than 12 Months, Fair Value	0	1,032
12 Months or More, Fair Value	0	0
Total, Fair Value	0	1,032
Unrealized Losses [Abstract]
Less than 12 Months, Unrealized Losses	0	(4)
12 Months or More, Unrealized Losses	0	0
Total, Unrealized Losses	0	(4)
US government sponsored mortgage-backed securities [Member]
Amortized cost and fair value of investment securities held to maturity [Abstract]
Amortized Cost	635	653
Gross Unrealized Gains	59	48
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 694	$ 701