Allowance for Loan Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Ending allowance balance attributable to loans:
Individually evaluated for impairment	$ 1,497		$ 1,652
Collectively evaluated for impairment	3,295		3,084
Acquired with deteriorated credit quality	0		0
Ending balance	4,792	4,228
Allowance for loan losses:
Beginning balance	4,736	4,182
Provisions for loan losses	250	475
Charge-offs	(317)	(485)
Recoveries	123	56
Ending balance	4,792	4,228
Residential
Ending allowance balance attributable to loans:
Individually evaluated for impairment	143		213
Collectively evaluated for impairment	797		709
Acquired with deteriorated credit quality	0		0
Ending balance	940	1,060
Allowance for loan losses:
Beginning balance	922	828
Provisions for loan losses	213	498
Charge-offs	(198)	(276)
Recoveries	3	10
Ending balance	940	1,060
Land
Ending allowance balance attributable to loans:
Individually evaluated for impairment	6		0
Collectively evaluated for impairment	63		71
Acquired with deteriorated credit quality	0		0
Ending balance	69	99
Allowance for loan losses:
Beginning balance	71	93
Provisions for loan losses	(2)	10
Charge-offs	0	(4)
Recoveries	0	0
Ending balance	69	99
Construction
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	50		0
Acquired with deteriorated credit quality	0		0
Ending balance	50	35
Allowance for loan losses:
Beginning balance	0	33
Provisions for loan losses	50	2
Charge-offs	0	0
Recoveries	0	0
Ending balance	50	35
Commercial Real Estate
Ending allowance balance attributable to loans:
Individually evaluated for impairment	258		275
Collectively evaluated for impairment	1,033		1,035
Acquired with deteriorated credit quality	0		0
Ending balance	1,291	924
Allowance for loan losses:
Beginning balance	1,310	1,269
Provisions for loan losses	(33)	(345)
Charge-offs	0	0
Recoveries	14	0
Ending balance	1,291	924
Commercial Business
Ending allowance balance attributable to loans:
Individually evaluated for impairment	1,065		1,098
Collectively evaluated for impairment	161		125
Acquired with deteriorated credit quality	0		0
Ending balance	1,226	1,175
Allowance for loan losses:
Beginning balance	1,223	1,160
Provisions for loan losses	(46)	12
Charge-offs	0	0
Recoveries	49	3
Ending balance	1,226	1,175
Home Equity and Second Mortgage
Ending allowance balance attributable to loans:
Individually evaluated for impairment	25		66
Collectively evaluated for impairment	861		853
Acquired with deteriorated credit quality	0		0
Ending balance	886	651
Allowance for loan losses:
Beginning balance	919	400
Provisions for loan losses	(33)	361
Charge-offs	(14)	(114)
Recoveries	14	4
Ending balance	886	651
Other Consumer
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	330		291
Acquired with deteriorated credit quality	0		0
Ending balance	330	284
Allowance for loan losses:
Beginning balance	291	399
Provisions for loan losses	101	(63)
Charge-offs	(105)	(91)
Recoveries	43	39
Ending balance	$ 330	$ 284