Loans and Allowance for Loan Losses - Summary of Impaired Financial Receivables (Summary of Purchased Non-Covered Impaired Loans) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings not included above	$ 20,900,000	$ 23,900,000
Purchased Non-Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	6,659,000
Troubled debt restructurings not included above	5,938,000
Total impaired loans	12,597,000
Impaired loans not requiring a related allowance	12,597,000
Impaired loans requiring a related allowance
Allowance related to impaired loans
Average investment in impaired loans	242,000
Interest income recognized on impaired loans
Foregone interest income on impaired loans