Summary of Other Noninterest Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Other Noninterest Expense [Line Items]
Telephone	$ 1,547	$ 1,416	$ 3,331	$ 2,766
Client services	1,739	1,037	2,992	1,839
Data processing services	1,310	1,429	2,715	2,492
Tax credit fund amortization	962	1,101	2,020	2,154
Postage and supplies	628	562	1,253	1,084
Dues and publications	557	327	1,031	701
Net gain from note repurchases and termination of corresponding interest rate swaps		(3,123)		(3,123)
Other	2,675	2,287	3,883	4,986
Total other noninterest expense	$ 9,418	$ 5,036	$ 17,225	$ 12,899