Loans - Summary of Impaired Financial Receivables (Summary of Purchased Non-Covered Impaired Loans) (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings not included above	$ 21,200,000	$ 23,300,000	$ 20,900,000
Purchased Non-Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	15,318,000		6,659,000
Troubled debt restructurings not included above	5,191,000		5,938,000
Total impaired loans	20,509,000		12,597,000
Impaired loans not requiring a related allowance	20,509,000		12,597,000
Impaired loans requiring a related allowance
Allowance related to impaired loans
Average investment in impaired loans	16,553,000		242,000
Interest income recognized on impaired loans
Foregone interest income on impaired loans	$ 563,000