Other Real Estate - Company's Other Real Estate (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014 Property	Dec. 31, 2013 Property	Dec. 31, 2012 Property
Real Estate By Property [Line Items]
Number of Properties	40	41	32
Balance	$ 7,646	$ 9,630	$ 7,008
Construction, Land Development and Other Land [Member]
Real Estate By Property [Line Items]
Number of Properties	15	18	11
Balance	5,034	4,887	2,834
1 - 4 Family Residential Properties [Member]
Real Estate By Property [Line Items]
Number of Properties	10	6	6
Balance	431	180	576
Nonfarm Nonresidential [Member]
Real Estate By Property [Line Items]
Number of Properties	14	17	14
Balance	2,030	4,563	3,573
Other [Member]
Real Estate By Property [Line Items]
Number of Properties	1		1
Balance	$ 151		$ 25