Segments - Financial Information of Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	$ 59,096	$ 57,808	$ 55,850	$ 55,019	$ 53,353	$ 53,669	$ 52,611	$ 43,916	$ 227,774	$ 203,548	$ 160,523
Interest expense	6,638	6,353	6,142	5,382	4,468	4,073	3,800	3,657	24,515	15,997	12,481
NET INTEREST INCOME									203,259	187,551	148,042
Provision for loan losses	5,586	2,516	4,848	5,014	3,915	3,206	2,059	1,207	17,965	10,388	1,715
Noninterest income	12,922	13,448	12,448	15,817	13,084	12,481	13,417	12,084	54,635	51,033	46,338
Noninterest expense									136,651	130,160	112,646
Depreciation expense									4,966	4,739	3,465
Amortization of intangible assets									1,615	1,818	1,129
Provision (benefit) for income taxes	$ 6,510	$ 7,367	$ 5,496	$ 5,931	$ 6,814	$ 6,407	$ 6,498	$ 4,680	25,305	24,398	17,515
Net Income									71,392	67,081	57,910
Operating Segments | Community Banking
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income									227,756	203,439	160,403
Interest expense									24,851	16,678	13,989
NET INTEREST INCOME									202,905	186,761	146,414
Provision for loan losses									17,965	10,388	1,715
Noninterest income									37,717	34,106	29,443
Noninterest expense									120,744	115,998	97,733
Depreciation expense									4,905	4,664	3,387
Amortization of intangible assets									1,543	1,738	1,039
Provision (benefit) for income taxes									24,872	23,209	16,311
Net Income									70,593	64,870	55,672
Operating Segments | Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income									2	2	2
Interest expense									0	0	0
NET INTEREST INCOME									2	2	2
Provision for loan losses									0	0	0
Noninterest income									4,794	5,035	5,279
Noninterest expense									4,582	4,365	4,313
Depreciation expense									45	50	51
Amortization of intangible assets									50	50	51
Provision (benefit) for income taxes									42	200	303
Net Income									77	372	563
Operating Segments | Wealth Management
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income									459	508	518
Interest expense									0	0	0
NET INTEREST INCOME									459	508	518
Provision for loan losses									0	0	0
Noninterest income									10,443	11,412	11,297
Noninterest expense									9,751	9,037	9,173
Depreciation expense									16	25	27
Amortization of intangible assets									22	30	39
Provision (benefit) for income taxes									391	989	901
Net Income									722	1,839	1,675
Eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income									(443)	(401)	(400)
Interest expense									(336)	(681)	(1,508)
NET INTEREST INCOME									(107)	280	1,108
Provision for loan losses									0	0	0
Noninterest income									1,681	480	319
Noninterest expense									1,574	760	1,427
Depreciation expense									0	0	0
Amortization of intangible assets									0	0	0
Provision (benefit) for income taxes									0	0	0
Net Income									$ 0	$ 0	$ 0