Acquired Loans (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Covered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	$ 47,589	$ 52,041
Less allowance for loan losses, acquired loans	4,497	4,190
Net acquired loans	43,092	47,851
Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	1,003,127	81,523
Less allowance for loan losses, acquired loans	1,961	1,885
Net acquired loans	1,001,166	79,638
Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Covered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	3,875	3,924
Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	138,442	10,056
Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Covered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	20,980	23,990
Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	209,658	19,404
Real Estate Secured Financing Receivable [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Covered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	17,355	18,407
Real Estate Secured Financing Receivable [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	339,953	45,649
Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Covered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	3,365	3,567
Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	32,208	669
Commercial And Industrial Loans [Member] | Covered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	648	747
Commercial And Industrial Loans [Member] | Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	235,286	3,035
Consumer Loans Financing Receivable [Member] | Covered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	179	177
Consumer Loans Financing Receivable [Member] | Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	32,694	2,610
Other Loans Financing Receivable [Member] | Covered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	1,187	1,229
Other Loans Financing Receivable [Member] | Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	$ 14,886	$ 100