Loans and Allowance for Loan Losses - Additional Information (Detail) (USD $)	12 Months Ended					12 Months Ended					12 Months Ended
	Dec. 31, 2013 Category	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Non-Covered Loan [Member]	Dec. 31, 2012 Non-Covered Loan [Member]	Dec. 31, 2013 Covered Loans [Member]	Dec. 31, 2012 Covered Loans [Member]	Dec. 31, 2011 Covered Loans [Member]	Dec. 31, 2010 Covered Loans [Member]	Dec. 31, 2009 Covered Loans [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Minimum [Member] Troubled Debt Restructuring [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased non-covered loans	$ 448,800,000
Covered loans acquired in FDIC-assisted transactions	390,200,000	507,700,000
Past due loan accrued											90 days
Loans on nonaccrual status, excluding purchased non-covered and covered loans	29,200,000	38,900,000	70,800,000
Purchased non-covered loans on nonaccrual status	6,700,000
Purchase of non-covered loans		0
Nonaccrual loans						69,152,000	115,712,000	159,999,000	88,153,000	25,791,000	200,000	100,000
Number of risk grading system category	9
Loan-to-value ratio											110.00%
Modified loans	30,400,000	40,300,000				20,990,000	21,536,000
Troubled debt restructurings	20,900,000	23,900,000		7,200,000	0	22,243,000	17,090,000	19,884,000
Troubled debt restructurings, previous charge-offs	2,100,000	1,900,000		0		1,600,000	6,400,000
Allowance for loan losses allocated to troubled debt restructurings	432,000	640,000
Commitments to lend additional funds	0			0		0
Troubled debt restructurings, provision for loan loss expense	$ 1,500,000	$ 2,600,000	$ 2,400,000