Loans - Schedule of Average Recorded Investment in Impaired Loans and Related Interest Income Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Average recorded investment:
Average recorded investment in impaired loans	$ 8,530	$ 9,179
Interest income recognized:
Interest income recognized on a cash basis on impaired loans	84	72
Commercial [Member]
Average recorded investment:
Average recorded investment in impaired loans	6,016	5,857
Interest income recognized:
Interest income recognized on a cash basis on impaired loans	65	51
Commercial Real Estate [Member]
Average recorded investment:
Average recorded investment in impaired loans	984	1,704
Interest income recognized:
Interest income recognized on a cash basis on impaired loans	4	5
Residential Real Estate [Member]
Average recorded investment:
Average recorded investment in impaired loans	1,530	1,618
Interest income recognized:
Interest income recognized on a cash basis on impaired loans	$ 15	$ 16