Credit Risk Profile by Internally Assigned Grade (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Residential	$ 10,889	[1]	$ 12,338	[1]
Consumer	36,509	[1]	37,829	[1]
Internally Assigned Grade | Pass Credit
Financing Receivable, Recorded Investment [Line Items]
Residential	8,920	[1]	10,833	[1]
Consumer	31,021	[1]	33,307	[1]
Internally Assigned Grade | Grade 6 Special Mention
Financing Receivable, Recorded Investment [Line Items]
Residential	697	[1]	243	[1]
Consumer	1,579	[1]	480	[1]
Internally Assigned Grade | Grade 7 Substandard
Financing Receivable, Recorded Investment [Line Items]
Residential	1,272	[1]	1,262	[1]
Consumer	$ 3,909	[1]	$ 4,042	[1]

[1] Credit quality indicators are reviewed and updated as applicable on an ongoing basis in accordance with credit policies.