Business Combinations (Details Textuals) (USD $)	6 Months Ended				6 Months Ended		6 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended				6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2010	Jun. 30, 2011	Dec. 31, 2010	May 14, 2010	Jun. 30, 2011 First Bank Branches [Member]	Feb. 19, 2010 First Bank Branches [Member]	Jun. 30, 2011 Other Loan [Member] Midwest Bank and Trust Company [Member]	Jun. 30, 2010 Midwest Bank and Trust Company [Member]	Sep. 30, 2010 Midwest Bank and Trust Company [Member]	Jun. 30, 2011 Midwest Bank and Trust Company [Member]	Jun. 30, 2010 Midwest Bank and Trust Company [Member]	Jun. 14, 2010 Midwest Bank and Trust Company [Member]	May 14, 2010 Midwest Bank and Trust Company [Member]	Jun. 30, 2011 Commercial [Member] George Washington Savings Bank [Member]	Jun. 30, 2011 Single Family Residential Mortgage Loan [Member] George Washington Savings Bank [Member]	Jun. 30, 2010 George Washington Savings Bank [Member]	Mar. 31, 2010 George Washington Savings Bank [Member]	Jun. 30, 2011 George Washington Savings Bank [Member]	Feb. 19, 2010 George Washington Savings Bank [Member]
Business Acquisition [Line Items]
Cash received to assume net liabilities	$ 985,506,000				$ 832,500,000													$ 40,200,000
Cash payment made by bank to FDIC												227,500,000
Number of Branches Purchased using options									10							3
Reimbursement Period Under Loss Sharing Agreements							10 years							10 years
Loss Sharing Agreement Period for commercial loans														5 years
Loss Sharing Agreement Period for other than single family residential mortgage loans							5 years
Bank reimbursement period To FDIC							8 years							8 years
Estimated fair value of covered loans													1,800,000,000						177,800,000
Expected reimbursement for losses on the Covered Loans										260,700,000								88,700,000
Estimated fair value of the covered other real estate													26,200,000						11,500,000
Expected reimbursement for losses to be incurred by the Bank on covered other real estate										2,200,000								11,300,000
Increase in estimated fair value of the Covered Loans				23,900,000									39,400,000						6,300,000
Decrease in estimated fair value of the investment securities													39,400,000
Increase (Decrease) in FDIC loss share receivable on the Covered Loans																			7,500,000
Increase in other liabilities											2,300,000						5,200,000
FDIC Loss Increase In Accrued Interest													5,400,000
FDIC loss share receivable Increase in other assets													20,600,000
Goodwill	460,045,000	460,044,000	460,044,000							2,200,000
Bargain purchase gain																		1,000,000
Percent of asset discount under loss sharing agreements																		25.00%
Asset discount received																		47,000,000
Bargain purchase, net of tax																		700,000
Percent of cumulative shared loss payments under loss sharing agreements										25.00%								25.00%
Percent of excess threshold paid by The Bank under loss sharing agreements																		50.00%
Estimated True Up Liability										7,700,000									5,200,000
Increase in bargain purchase gain																	4,000,000
Reduction in true-up liability										6,300,000
Period after closing date fair value estimates subject to change																		Up to one year
Number of branches						24
Combined Purchase Price									25,100,000							4,300,000
Goodwill impairment loss								5,600,000
Percent of losses under loss sharing agreements below threshold reimbursable by FDIC										80.00%								80.00%
Percent of losses under loss sharing agreements above threshold reimbursable by FDIC										80.00%								95.00%
Threshold for losses under loss sharing agreements reimbursable by FDIC																		172,000,000
Percent of recoveries under loss sharing agreements below threshold reimbursable by the Bank										80.00%								80.00%
Percent of recoveries under loss sharing agreements above threshold reimbursable by the Bank										80.00%								95.00%
Percent of losses under loss sharing agreement below threshold paid by FDIC																		80.00%
Percent of recoveries under loss sharing agreements above threshold paid by FDIC																		95.00%
Percent of FDIC intrinsic loss estimate																		20.00%
FDIC intrinsic loss estimate																		152,000,000
Percent of Asset premium paid									25.00%
Asset premium paid										20,000,000
Decrease in bargain purchase gain																	$ 5,200,000
Reimbursement period to FDIC															10 years