Location and Amounts Recognized for Fair Value Hedges (Detail) (Fair Value Hedges, USD $) In Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Increase (decrease) to Interest Income	$ (236)	$ (251)	$ (471)	$ (511)
Interest Rate Contracts \| Loans \| Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Increase (decrease) to Interest Income	$ (236)	$ (251)	$ (471)	$ (511)

Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-Subparagraph a(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624171-113959

Name:	us-gaap_GainLossOnFairValueHedgesRecognizedInEarnings
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration