Investment Securities - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Maturity of contract	less than one year
Approximate year of maturity	30 years
Gross Unrealized Losses	$ 47,666,000	$ 28,960,000
Amortized Cost	1,350,466,000	1,169,613,000
Net securities (losses) gains	(1,158,000)	192,000	2,185,000
Available-for-sale securities pledged as collateral	594,900,000	631,000,000
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses	1,300,000
Amortized Cost	6,600,000
Net securities (losses) gains	200,000
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Non-bank subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Sale of available securities	200,000
Single issuer trust preferred securities [Member] | Non-bank subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Sale of available securities	$ 5,100,000