Loans - Summary of Impaired Financial Receivables (Summary of 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
Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	59,781,000	98,515,000	69,152,000
Troubled debt restructurings not included above	22,775,000	21,592,000	22,243,000
Total impaired loans	82,556,000	120,107,000	91,395,000
Impaired loans not requiring a related allowance	82,556,000	120,107,000	91,395,000
Impaired loans requiring a related allowance
Allowance related to impaired loans
Average investment in impaired loans	86,976,000	127,507,000	110,830,000
Interest income recognized on impaired loans	155,000	169,000	968,000
Foregone interest income on impaired loans	$ 10,000	$ 147,000	$ 330,000