Fair Value - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans, recorded investment	$ 23,688		$ 23,688		$ 24,657
Impaired loans allowance	4,074		4,074		3,415
Collateral Dependent Loans [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans, recorded investment	7,030		7,030		7,423
Impaired loans allowance	2,116		2,116		$ 2,250
Impaired loans, additional provisions	$ 60	$ 280	$ 63	$ 630