Segments - Total Assets by Reportable Operating Segment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	$ 6,318,354	$ 4,964,686
Community Banking
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	6,305,046	4,954,728
Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	9,619	7,468
Wealth Management
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	$ 3,689	$ 2,490