Impaired Loans (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Impaired Loans:
Impaired loans without a valuation allowance	$ 4,622	$ 4,702
Impaired loans with a valuation allowance	4,499	4,858
Total impaired loans	9,121	9,560
Allowance for loan losses on impaired loans at period End	1,008	968
Total nonaccrual loans	6,513	6,056	$ 64
Past due 90 days or more and still accruing	92	669
Average investment in impaired loans	$ 9,101	$ 7,077