Segments - Financial Information of Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	$ 55,019	$ 43,916
Interest expense	5,382	3,657
NET INTEREST INCOME	49,637	40,259
Provision for loan losses	5,014	1,207
Noninterest income	15,817	12,084
Noninterest expense	36,758	32,243
Depreciation expense	1,200	1,030
Amortization of intangible assets	458	348
Provision for income taxes	5,931	4,680
Net Income	16,093	12,835
Operating Segments | Community Banking
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	55,016	43,887
Interest expense	5,438	3,889
NET INTEREST INCOME	49,578	39,998
Provision for loan losses	5,014	1,207
Noninterest income	11,346	7,537
Noninterest expense	33,169	28,687
Depreciation expense	1,186	1,011
Amortization of intangible assets	439	326
Provision for income taxes	5,613	4,256
Net Income	15,503	12,048
Operating Segments | Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	1
NET INTEREST INCOME	1
Noninterest income	1,624	1,553
Noninterest expense	1,254	1,137
Depreciation expense	10	12
Amortization of intangible assets	12	13
Provision for income taxes	122	137
Net Income	227	254
Operating Segments | Wealth Management
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	128	140
NET INTEREST INCOME	128	140
Noninterest income	2,747	2,916
Noninterest expense	2,305	2,220
Depreciation expense	4	7
Amortization of intangible assets	7	9
Provision for income taxes	196	287
Net Income	363	533
Eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	(126)	(111)
Interest expense	(56)	(232)
NET INTEREST INCOME	(70)	121
Noninterest income	100	78
Noninterest expense	$ 30	$ 199