Bank Premises and Equipment - Components of Bank Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Bank premises and equipment, gross	$ 23,958	$ 21,054
Accumulated depreciation	(12,427)	(10,244)
Total	11,531	10,810
Leasehold improvements
Property, Plant and Equipment [Line Items]
Bank premises and equipment, gross	$ 12,531	11,680
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Expected useful life (years)	3 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Expected useful life (years)	25 years
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Bank premises and equipment, gross	$ 5,312	4,504
Furniture, fixtures and equipment | Minimum
Property, Plant and Equipment [Line Items]
Expected useful life (years)	5 years
Furniture, fixtures and equipment | Maximum
Property, Plant and Equipment [Line Items]
Expected useful life (years)	10 years
IT equipment
Property, Plant and Equipment [Line Items]
Bank premises and equipment, gross	$ 5,909	4,696
IT equipment | Minimum
Property, Plant and Equipment [Line Items]
Expected useful life (years)	3 years
IT equipment | Maximum
Property, Plant and Equipment [Line Items]
Expected useful life (years)	5 years
Automobiles
Property, Plant and Equipment [Line Items]
Bank premises and equipment, gross	$ 206	$ 174
Automobiles | Minimum
Property, Plant and Equipment [Line Items]
Expected useful life (years)	5 years
Automobiles | Maximum
Property, Plant and Equipment [Line Items]
Expected useful life (years)	10 years