Loans - Non-Covered Loans Modified as TDR (Detail) (Troubled Debt Restructurings Subsequently Defaulted [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	12
Recorded Investment	$ 2,611
Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	10
Recorded Investment	2,389
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	2
Recorded Investment	$ 222