Loans - Schedule of Average Recorded Investment in Impaired Loans and Related Interest Income Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Average recorded investment:
Average recorded investment in impaired loans	$ 8,822	$ 9,472	$ 8,743	$ 9,327
Interest income recognized:
Interest income recognized on a cash basis on impaired loans	72	77	157	149
Commercial [Member]
Average recorded investment:
Average recorded investment in impaired loans	6,579	6,137	6,360	5,998
Interest income recognized:
Interest income recognized on a cash basis on impaired loans	56	54	122	105
Commercial Real Estate [Member]
Average recorded investment:
Average recorded investment in impaired loans	746	1,606	865	1,655
Interest income recognized:
Interest income recognized on a cash basis on impaired loans	2	4	6	9
Residential Real Estate [Member]
Average recorded investment:
Average recorded investment in impaired loans	1,497	1,729	1,518	1,674
Interest income recognized:
Interest income recognized on a cash basis on impaired loans	$ 14	$ 19	$ 29	$ 35