Loans - Analysis of Allowance for Credit Losses (Detail) (USD $)	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	$ 5,386,000	$ 5,221,000
Charge Offs	(1,262,000)	(891,000)
Recoveries	374,000	286,000
Provision	858,000	738,000
Other Non-interest expense related to unfunded	1,000	32,000
Ending Balance	5,357,000	5,386,000
Ending balance: individually evaluated for impairment	516,000	865,000
Ending balance: collectively evaluated for impairment	4,841,000	4,521,000
Ending balance: loans acquired with deteriorated credit quality	1,000	1,000
FINANCING RECEIVABLES:
Ending balance	576,113,000	501,402,000
Ending balance: individually evaluated for impairment	2,440,000	4,591,000
Ending balance: collectively evaluated for impairment	573,673,000	496,811,000
Ending balance: loans acquired with deteriorated credit quality	540,000	548,000
Consumer Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	368,000	261,000
Charge Offs	(147,000)	(246,000)
Recoveries	20,000	61,000
Provision	16,000	292,000
Other Non-interest expense related to unfunded
Ending Balance	257,000	368,000
Ending balance: individually evaluated for impairment	78,000	70,000
Ending balance: collectively evaluated for impairment	179,000	298,000
Ending balance: loans acquired with deteriorated credit quality	1,000	1,000
FINANCING RECEIVABLES:
Ending balance	92,438,000	80,287,000
Ending balance: individually evaluated for impairment	300,000	648,000
Ending balance: collectively evaluated for impairment	92,138,000	79,639,000
Ending balance: loans acquired with deteriorated credit quality	540,000	548,000
Agricultural Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	113,000	140,000
Charge Offs
Recoveries
Provision	18,000	(27,000)
Other Non-interest expense related to unfunded
Ending Balance	131,000	113,000
Ending balance: individually evaluated for impairment	9,000
Ending balance: collectively evaluated for impairment	122,000	113,000
Ending balance: loans acquired with deteriorated credit quality
FINANCING RECEIVABLES:
Ending balance	44,301,000	40,143,000
Ending balance: individually evaluated for impairment	88,000
Ending balance: collectively evaluated for impairment	44,213,000	40,143,000
Ending balance: loans acquired with deteriorated credit quality
Agriculture [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	290,000	266,000
Charge Offs		(6,000)
Recoveries	5,000	12,000
Provision	31,000	18,000
Other Non-interest expense related to unfunded
Ending Balance	326,000	290,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	326,000	290,000
Ending balance: loans acquired with deteriorated credit quality
FINANCING RECEIVABLES:
Ending balance	65,449,000	57,770,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	65,449,000	57,770,000
Ending balance: loans acquired with deteriorated credit quality
Commercial Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	1,749,000	2,088,000
Charge Offs	(164,000)	(98,000)
Recoveries	23,000	7,000
Provision	499,000	(248,000)
Other Non-interest expense related to unfunded
Ending Balance	2,107,000	1,749,000
Ending balance: individually evaluated for impairment	295,000	25,000
Ending balance: collectively evaluated for impairment	1,812,000	1,724,000
Ending balance: loans acquired with deteriorated credit quality
FINANCING RECEIVABLES:
Ending balance	248,893,000	199,999,000
Ending balance: individually evaluated for impairment	1,675,000	877,000
Ending balance: collectively evaluated for impairment	247,218,000	199,122,000
Ending balance: loans acquired with deteriorated credit quality
Commercial and Industrial [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	2,183,000	1,947,000
Charge Offs	(513,000)	(47,000)
Recoveries	141,000	30,000
Provision	(452,000)	253,000
Other Non-interest expense related to unfunded
Ending Balance	1,359,000	2,183,000
Ending balance: individually evaluated for impairment	134,000	770,000
Ending balance: collectively evaluated for impairment	1,225,000	1,413,000
Ending balance: loans acquired with deteriorated credit quality
FINANCING RECEIVABLES:
Ending balance	103,856,000	102,923,000
Ending balance: individually evaluated for impairment	377,000	3,066,000
Ending balance: collectively evaluated for impairment	103,479,000	99,857,000
Ending balance: loans acquired with deteriorated credit quality
Consumer (incl. Credit Cards) [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	268,000	315,000
Charge Offs	(438,000)	(494,000)
Recoveries	185,000	176,000
Provision	277,000	271,000
Other Non-interest expense related to unfunded
Ending Balance	292,000	268,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	292,000	268,000
Ending balance: loans acquired with deteriorated credit quality
FINANCING RECEIVABLES:
Ending balance	21,176,000	20,280,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	21,176,000	20,280,000
Ending balance: loans acquired with deteriorated credit quality
Unfunded Loan Commitment & Letters of Credit [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	162,000	130,000
Charge Offs
Recoveries
Provision
Other Non-interest expense related to unfunded	1,000	32,000
Ending Balance	163,000	162,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	163,000	162,000
Ending balance: loans acquired with deteriorated credit quality
FINANCING RECEIVABLES:
Ending balance
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment
Ending balance: loans acquired with deteriorated credit quality
Unallocated [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	253,000	74,000
Charge Offs
Recoveries
Provision	469,000	179,000
Other Non-interest expense related to unfunded
Ending Balance	722,000	253,000
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment	722,000	253,000
Ending balance: loans acquired with deteriorated credit quality
FINANCING RECEIVABLES:
Ending balance
Ending balance: individually evaluated for impairment
Ending balance: collectively evaluated for impairment
Ending balance: loans acquired with deteriorated credit quality

Loans - Analysis of Allowance for Credit Losses (Detail) (USD $)

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

ALLOWANCE FOR CREDIT LOSSES:

Beginning balance

$ 5,386,000

$ 5,221,000

Charge Offs

(1,262,000)

(891,000)

Recoveries