Other Noninterest Income and Other Noninterest Expense - Summary of Other Noninterest Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Other Income and Expenses [Abstract]
Telephone	$ 1,557	$ 1,784
Client services	1,935	1,253
Data processing services	1,912	1,405
Tax credit fund amortization	1,317	1,058
Postage and supplies	538	625
Dues and publications	458	474
Other	2,218	1,208
Total other noninterest expense	$ 9,935	$ 7,807