Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Significant Accounting Policies [Line Items]
Maximum refinement period of fair values after closing date of acquisition	1 year
Total of the average daily required reserve	$ 11,600,000	$ 14,000,000
Carrying amount of bank owned real estate	10,300,000	3,600,000
Company stock-based compensation cost	1,000,000	1,000,000	785,000
Anti-dilutive common shares excluded	324,000	418,000	414,000
Fair value of derivative instruments, asset	1,180,000	1,169,000
Fair Value Hedging [Member]
Significant Accounting Policies [Line Items]
Cash flow for the purpose of converting floating rate loans to a fixed rate	370,000	3,000,000
Junior Subordinated Debentures [Member] | Cash Flow Hedging [Member]
Significant Accounting Policies [Line Items]
Cash flow for the purpose of converting floating rate loans to a fixed rate	$ 37,100,000	$ 37,100,000	$ 37,100,000
Buildings [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	40 years
Minimum [Member]
Significant Accounting Policies [Line Items]
Intangible assets amortized over an estimated useful life	3 years
Minimum [Member] | Furniture and Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Minimum [Member] | Software and Computer Related Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Maximum [Member]
Significant Accounting Policies [Line Items]
Intangible assets amortized over an estimated useful life	10 years
Maximum [Member] | Furniture and Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	20 years
Maximum [Member] | Software and Computer Related Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives	5 years