Loans and Other Repossessed Assets Acquired (Detail) - Defaulted TDRs with structure or rate modifications (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Dec. 31, 2012
#	6		8
Pre-default balance	$ 1,890	[1]	$ 3,338	[1]
Acquired covered loans included above	1		2
Acquired covered loans included above	523	[1]	300	[1]
Performing Financing Receivable [Member] | Home Equity Loans [Member]
Pre-default balance	0		0
Performing Financing Receivable [Member] | Commercial Real Estate [Member]
Pre-default balance	0		662
Performing Financing Receivable [Member] | Residential 1-4 Family [Member]
Pre-default balance	0		0
Performing Financing Receivable [Member]
Pre-default balance	0		662
Acquired covered loans included above	0		0
Nonperforming Financing Receivable [Member] | Home Equity Loans [Member]
Pre-default balance	601		1,387
Nonperforming Financing Receivable [Member] | Commercial Real Estate [Member]
Pre-default balance	897		1,289
Nonperforming Financing Receivable [Member] | Residential 1-4 Family [Member]
Pre-default balance	392		0
Nonperforming Financing Receivable [Member]
Pre-default balance	1,890		2,676
Acquired covered loans included above	523		300
Home Equity Loans [Member]
#	2		3
Pre-default balance	601	[1]	1,387	[1]
Commercial Real Estate [Member]
#	3		5
Pre-default balance	897	[1]	1,951	[1]
Residential 1-4 Family [Member]
#	1		0
Pre-default balance	$ 392	[1]	$ 0	[1]

[1] There were no acquired non-covered TDRs in the above noted periods.