Summary of Other Noninterest Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Other Noninterest Expense [Line Items]
Telephone	$ 5,835		$ 4,952	$ 4,202
Data processing services	4,811		4,060	3,025
Client services	4,594		2,716	1,923
Tax credit fund amortization	4,474		3,965	4,614
Postage and supplies	2,162		2,198	2,985
Dues and publications	1,570		1,519	1,872
Net gain from note repurchases and termination of corresponding interest rate swaps	(3,123)	[1]
Other	10,499		7,081	6,102
Total other noninterest expense	$ 30,822		$ 26,491	$ 24,723

[1] Represents gains from the repurchase of $108.6 million of our 5.70% Senior Notes and $204.0 million of our 6.05% Subordinated Notes and the termination of the corresponding portions of interest rate swaps in 2011. For more information, see Note 11-"Short-Term Borrowings and Long-Term Debt."