Covered Loans, Covered Other Real Estate and FDIC Indemnification Asset (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Apr. 15, 2011
Covered loans acquired and activity [Abstract]
Contractually required principal and interest	$ 145,864,000
Nonaccretable difference	(38,345,000)
Cash flows expected to be collected	107,519,000
Accretable yield	(13,579,000)			(13,579,000)
Other revolving loans	3,830,000
Fair value of covered loans at acquisition date	97,770,000
Accretion	4,890,000
Payments received	(30,337,000)
Change in expected cash flows	4,481,000
Less allowance for loan losses	(502,000)	0
Covered loans	76,804,000	0
Covered loans not accounted for under FASB ASC Topic 310-30 classified as nonaccrual loans	491,000
Net covered loans	76,302,000	0
Loans acquired subject to loss share agreements with the FDIC	97,800,000
Percentage of covered loans to total acquired loans (in hundredths)	91.00%
Acquired revolving credit agreements	3,800,000
Increase in carrying value of covered loans	4,500,000
Increase in accretable yield of covered loans	7,600,000
Covered Other Real Estate [Abstract]
Covered other real estate	6,331,000	0		7,485,000
Changes in accretable yield on covered loans [Abstract]
Accretable yield acquired, beginning of period				(13,579,000)
Accretion	4,347,000
Change in expected cash flows	(7,644,000)
Accretable yield, end of period	(16,876,000)
Allowance for loan loss [Abstract]
Provision for covered loan losses	624,000	0	0
Loans charged-off	(218,000)
Recoveries	96,000
Net charge-offs	(122,000)
Balance	502,000
FDIC Indemnification Asset [Abstract]
FDIC indemnification asset	28,348,000	0		33,333,000
Accretion Income	185,000
Loss-share payments received from FDIC	(986,000)
Change in expected cash flows	(4,157,000)
Change in FDIC true-up provision	(27,000)
FDIC indemnification asset	28,348,000	0		33,333,000
FDIC true-up provision	601,000
Write-down of the FDIC indemnification asset	4,200,000
Other Real Estate Secured Financing Receivable [Member]
Covered Other Real Estate [Abstract]
Covered other real estate	6,331,000
Real Estate Secured Financing Receivable [Member] | Construction, Land Development And Other Financing Receivable [Member]
Covered loans acquired and activity [Abstract]
Covered loans	4,209,000
Covered Other Real Estate [Abstract]
Covered other real estate	1,304,000
Real Estate Secured Financing Receivable [Member] | Residential 1-4 Family Financing Receivable [Member]
Covered loans acquired and activity [Abstract]
Covered loans	31,874,000
Covered Other Real Estate [Abstract]
Covered other real estate	889,000
Real Estate Secured Financing Receivable [Member] | Nonresidential Nonfarm Properties Financing Receivables [Member]
Covered loans acquired and activity [Abstract]
Covered loans	30,889,000
Covered Other Real Estate [Abstract]
Covered other real estate	4,022,000
Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member]
Covered loans acquired and activity [Abstract]
Covered loans	5,126,000
Covered Other Real Estate [Abstract]
Covered other real estate	116,000
Real Estate Secured Financing Receivable [Member]
Covered Other Real Estate [Abstract]
Other real estate at acquisition	7,485,000
Transfers from covered loans	632,000
FASB ASC 310-30 adjustment for the residual recorded investment	(264,000)
Net transfers from covered loans	368,000
Disposals	(1,489,000)
Writedowns	(33,000)
Covered other real estate	6,331,000
Gain (loss), net on the sale of covered other real estate included in ORE/Foreclosure expenses	286,000
Other Loans Financing Receivable [Member]
Covered loans acquired and activity [Abstract]
Covered loans	1,445,000
Commercial And Industrial Loans Financing Receivable [Member]
Covered loans acquired and activity [Abstract]
Covered loans	2,971,000
Consumer Loans Financing Receivable [Member]
Covered loans acquired and activity [Abstract]
Covered loans	$ 290,000