Premises and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Amount paid under sale-leaseback arrangement	$ 376,000
Gain on sale of branch	297,000
Sale-leaseback transaction	15 year
Total lease expense	4,200,000	4,300,000	4,400,000
Premises and Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation included in noninterest expense	10,400,000	7,900,000	8,300,000
Software [Member]
Property, Plant and Equipment [Line Items]
Property Plant and Equipment, Gross, Amount Subject to Reduction in Estimated Useful Life	13,912,000
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property Plant and Equipment, Gross, Amount Subject to Reduction in Estimated Useful Life	$ 669,000
Previously Reported [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	6 years
Previously Reported [Member] | Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
After System Conversion in 2014 [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
After System Conversion in 2014 [Member] | Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	4 years