Segments - Financial Information of Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	$ 38,665	$ 37,843
Interest expense	3,074	4,174
NET INTEREST INCOME	35,591	33,669
Provision for loan losses	289	2,307
Noninterest income	11,416	14,806
Noninterest expense	27,777	30,248
Depreciation expense	821	937
Amortization of intangible assets	316	431
Provision (benefit) for income taxes	3,771	2,222
Net Income	14,033	12,330
Operating Segments [Member] | Community Banking [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	38,630	37,690
Interest expense	3,482	4,790
NET INTEREST INCOME	35,148	32,900
Provision for loan losses	289	2,307
Noninterest income	6,854	10,356
Noninterest expense	23,973	24,634
Depreciation expense	803	919
Amortization of intangible assets	292	405
Provision (benefit) for income taxes	3,365	2,854
Net Income	13,280	12,137
Operating Segments [Member] | Insurance [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	0	0
Interest expense	0	0
NET INTEREST INCOME	0	0
Provision for loan losses	0	0
Noninterest income	1,521	1,598
Noninterest expense	1,155	1,447
Depreciation expense	11	10
Amortization of intangible assets	13	13
Provision (benefit) for income taxes	120	45
Net Income	222	83
Operating Segments [Member] | Wealth Management [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	174	138
Interest expense	0	0
NET INTEREST INCOME	174	138
Provision for loan losses	0	0
Noninterest income	2,935	2,574
Noninterest expense	2,274	2,489
Depreciation expense	7	8
Amortization of intangible assets	11	13
Provision (benefit) for income taxes	286	92
Net Income	531	110
Eliminations [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	(139)	15
Interest expense	(408)	(616)
NET INTEREST INCOME	269	631
Provision for loan losses	0	0
Noninterest income	106	278
Noninterest expense	375	1,678
Depreciation expense	0	0
Amortization of intangible assets	0	0
Provision (benefit) for income taxes	0	(769)
Net Income	$ 0	$ 0