Loans - Schedule of Average Recorded Investment in Impaired Loans and Related Interest Income Recognized (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Average recorded investment:
Average recorded investment in impaired loans	$ 12,307	$ 9,011	$ 12,045	$ 9,530
Interest income recognized:
Total interest income recognized	92	90	203	201
Commercial [Member]
Average recorded investment:
Average recorded investment in impaired loans	6,983	3,773	6,593	3,988
Interest income recognized:
Total interest income recognized	41	40	102	85
Commercial Real Estate [Member]
Average recorded investment:
Average recorded investment in impaired loans	3,486	3,577	3,591	3,838
Interest income recognized:
Total interest income recognized	35	36	70	85
Residential Real Estate [Member]
Average recorded investment:
Average recorded investment in impaired loans	1,838	1,660	1,861	1,662
Interest income recognized:
Total interest income recognized	16	14	31	29
Construction & land development [Member]
Average recorded investment:
Average recorded investment in impaired loans		1		42
Interest income recognized:
Total interest income recognized				$ 2