Investment in Securities (Details Textual) (USD $)	6 Months Ended
Jun. 30, 2011	Jun. 30, 2012 Security	Dec. 31, 2011 Security
Investment in Securities (Textual) [Abstract]
Proceeds from sales of available-for-sale securities	$ 15,650,000
Gross realized gains	2,800,000
Gross realized losses	56,000
Income tax expense (benefit) related to gross gains	1,100,000
Income tax expense (benefit) related to gross losses	(23,000)
Security sales		$ 0
Number of corporate debt securities		1
Percentage of unrealized losses related to one corporate debt security caused primarily by changes in market interest rates		0.11%
Number of unrealized losses debt securities			9
Percentage of aggregate depreciation related to nine debt securities			0.80%

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Unrealized losses debt securities.

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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