LOAN PORTFOLIO - Selected Information on TDRs Includes Recorded Investment by Loan Class and Modification Type (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable Impaired [Line Items]
Forbearance agreements related to one construction relationship	$ 53.4	$ 74.6