v2.4.0.6
Securities with Unrealized Losses, Aggregated by Category and Period of Continuous Unrealized Loss (Parenthetical) (Detail)
Mar. 31, 2013
Investment
Dec. 31, 2012
Investment
Investment [Line Items]    
Number of available for sale securities in unrealized loss positions 128 139
Number of held to maturity securities in unrealized loss positions 67 24