Loans and Allowance for Credit Losses - Schedule of Activity in Allowance for Loan Losses (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Charge-offs			$ 0		$ (200,000)
Provision	2,591,000	(1,724,000)	2,228,000	(4,572,000)
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	18,826,000	15,084,000	16,565,000	14,642,000	14,642,000
Charge-offs	(452,000)	(750,000)	(2,525,000)	(2,719,000)
Recoveries	610,000	472,000	2,196,000	2,501,000
Provision	819,000	(286,000)	3,567,000	96,000
Ending balance	19,803,000	14,520,000	19,803,000	14,520,000
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	17,764,000	26,595,000	22,401,000	31,289,000	31,289,000
Charge-offs	(401,000)	(432,000)	(1,608,000)	(3,233,000)
Recoveries	445,000	1,571,000	2,020,000	3,309,000
Provision	776,000	(2,864,000)	(4,229,000)	(6,495,000)
Ending balance	18,584,000	24,870,000	18,584,000	24,870,000
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	5,989,000	4,844,000	4,940,000	5,155,000	5,155,000
Charge-offs	(1,085,000)	(1,822,000)	(3,168,000)	(5,336,000)
Recoveries	570,000	1,132,000	2,232,000	3,540,000
Provision	795,000	657,000	2,265,000	1,452,000
Ending balance	6,269,000	4,811,000	6,269,000	4,811,000
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	3,573,000	2,795,000	3,239,000	3,677,000	3,677,000
Charge-offs	(192,000)	(501,000)	(391,000)	(1,212,000)
Recoveries	41,000	54,000	150,000	277,000
Provision	201,000	769,000	625,000	375,000
Ending balance	3,623,000	3,117,000	3,623,000	3,117,000
Loans and Leases Receivable Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	46,152,000	49,318,000	47,145,000	54,763,000	54,763,000
Charge-offs	(2,130,000)	(3,505,000)	(7,692,000)	(12,500,000)
Recoveries	1,666,000	3,229,000	6,598,000	9,627,000
Provision	2,591,000	(1,724,000)	2,228,000	(4,572,000)
Ending balance	$ 48,279,000	$ 47,318,000	$ 48,279,000	$ 47,318,000