Commitments, Guarantees, And Contingent Liabilities (Narrative) (Detail) (USD $)	Jun. 30, 2012 Month
Commitments Guarantees And Contingent Liabilities [Line Items]
Reserve for unfunded commitments, included in other liabilities	$ 8,200,000
Unamortized fees associated with standby letters of credit, included in other liabilities	760,000
Remaining weighted-average term, standby letters of credit	14
Contributions to other investment partnerships	3,700,000
Tax-credit investments	527,000
Maximum potential future payments guaranteed, third-party settlement	$ 3,800,000
Minimum [Member]
Commitments Guarantees And Contingent Liabilities [Line Items]
Remaining actual lives, standby letters of credit	1
Maximum [Member]
Commitments Guarantees And Contingent Liabilities [Line Items]
Remaining actual lives, standby letters of credit	19