Summary of Other Noninterest Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Disclosure Summary Of Other Noninterest Expense [Abstract]
Telephone	$ 1,619	$ 1,610	$ 4,950	$ 4,376
Client services	1,804	1,289	4,796	3,128
Data processing services	1,575	1,097	4,290	3,589
Tax credit fund amortization	941	1,212	2,961	3,366
Postage and supplies	591	641	1,844	1,725
Dues and publications	472	465	1,503	1,166
Net gain from note repurchases and termination of corresponding interest rate swaps	0	0	0	(3,123)
Other	1,961	3,240	5,844	8,226
Total other noninterest expense	$ 8,963	$ 9,554	$ 26,188	$ 22,453