Segments - Total Assets by Reportable Operating Segment (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	$ 4,706,987	$ 4,533,190
Community Banking [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	4,697,957	4,524,939
Insurance [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	7,146	6,926
Wealth Management [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	$ 1,884	$ 1,325