Fair Value Measurement of Assets and Liabilities - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended					3 Months Ended						3 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Minimum [Member]	Jun. 30, 2014 Maximum [Member]	Jun. 30, 2014 Significant Unobservable Inputs (Level 3) [Member]	Jun. 30, 2014 Available-for-sale Securities [Member]	Jun. 30, 2013 Available-for-sale Securities [Member]	Mar. 31, 2014 Available-for-sale Securities [Member]	Dec. 31, 2013 Available-for-sale Securities [Member]	Mar. 31, 2013 Available-for-sale Securities [Member]	Dec. 31, 2012 Available-for-sale Securities [Member]	Jun. 30, 2014 Non-Performing Loans [Member] Changes Measurement [Member]	Jun. 30, 2014 Non-Performing Loans [Member] Fair Value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Changes in unrealized losses on Level 3 securities							$ 0	$ 0
Transfer of loans to loans held for sale		27,329,000	0										2,300,000	7,900,000
Discount rate on impaired loans						26.40%
Impaired trust preferred securities ,fair value							26,029,000	79,112,000	26,911,000	28,523,000	77,920,000	71,674,000
Impaired collateral dependent loans, charge-offs	2,200,000	3,200,000
Collateral dependent impaired loans, recorded investment	23,600,000	23,600,000
Specific valuation allowance allocations	1,900,000	1,900,000
Reported net carrying amount of impaired loans	21,700,000	21,700,000
Valuation of loan servicing rights, discount rate		8.00%
Valuation of loan servicing rights, prepayment rate				0.00%	25.00%
Net recoveries of impairment charges	42,000	142,000
Fair Value, Unobservable Inputs Quantitative Information For Assets Measured On Nonrecurring Basis, Foreclosed Assets, Discount Rate		12.00%
Foreclosed assets measured at fair value upon initial recognition	12,700,000	12,700,000
Allowance for loan losses, charge-offs	527,000	2,000,000
Loss due to re-measurement of repossessed assets	$ 75,000	$ 1,900,000