Past Due Loan Trends for Corporation's Loans Receivable (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	$ 1,403	$ 2,580
60 - 89 Days Past Due	876	727
Greater Than 90 Days	10,347	11,951
Total Past Due	12,626	14,816
90 days Past Due & Still Accruing	16	442
Current	132,457	145,395
Total loans	145,099	160,653
Commercial Portfolio Segment | Commercial Non Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	38	485
60 - 89 Days Past Due	4	139
Greater Than 90 Days	744	996
Total Past Due	786	1,237
90 days Past Due & Still Accruing	16	383
Current	9,590	11,319
Total loans	10,392	12,939
Commercial Portfolio Segment | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	800	714
60 - 89 Days Past Due	278	472
Greater Than 90 Days	7,123	8,046
Total Past Due	8,201	9,232
Current	79,108	88,315
Total loans	87,309	97,547
Consumer Portfolio Segment | Other Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	225	422
60 - 89 Days Past Due	145	69
Greater Than 90 Days	1,700	2,052
Total Past Due	2,070	2,543
Current	19,182	19,753
Total loans	21,252	22,296
Consumer Portfolio Segment | Automobiles
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	13	69
60 - 89 Days Past Due	1
Greater Than 90 Days	10
Total Past Due	24	69
Current	797	874
Total loans	821	943
Consumer Portfolio Segment | Consumer Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	99	408
60 - 89 Days Past Due	175	47
Greater Than 90 Days	153	182
Total Past Due	427	578
90 days Past Due & Still Accruing		59
Current	14,009	13,953
Total loans	14,436	14,590
Residential Real Estate | Residential 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	228	482
60 - 89 Days Past Due	273
Greater Than 90 Days	617	675
Total Past Due	1,118	1,157
Current	9,771	11,181
Total loans	$ 10,889	$ 12,338