Other Noninterest (Loss) Income and Other Noninterest Expense - Summary of Other Noninterest Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Other Income and Expenses [Abstract]
Client services	$ 3,215	$ 1,920	$ 8,160	$ 5,711
Tax credit fund amortization	2,228	1,519	6,758	4,174
Data processing services	2,229	2,020	6,497	5,814
Telephone	1,931	1,571	5,217	4,640
Postage and supplies	763	559	2,248	1,777
Dues and publications	719	399	1,852	1,302
Other	4,711	2,661	9,381	6,855
Total other noninterest expense	$ 15,796	$ 10,649	$ 40,113	$ 30,273