Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net interest income	$ 36,729	$ 29,438	$ 111,484	$ 84,806
Provision for loan and lease losses	664	1,333	4,831	1,541
Net interest income after provision for loan and lease losses	36,065	28,105	106,653	83,265
Fees for wealth management services	10,343	9,651	31,309	28,761
Insurance commissions	1,754	1,373	5,349	3,079
Capital markets revenue	710	843	3,481	1,796
Service charges on deposit accounts	726	676	2,191	1,953
Loan servicing and other fees	559	548	1,720	1,570
Net gain on sale of loans	631	799	1,677	1,948
Net gain on sale of investment securities available for sale			7	73
Net gain on sale of OREO	5	0	292	(12)
Other operating income	3,546	1,622	11,859	4,428
Total noninterest income	18,274	15,584	57,885	43,596
Salaries and wages	16,528	13,602	48,750	39,632
Employee benefits	3,356	2,560	9,941	7,453
Occupancy and bank premises	2,717	2,485	8,464	7,258
Amortization of intangible assets	891	677	2,659	2,057
Professional fees	997	739	2,677	2,499
Other operating expenses	9,103	8,121	32,967	24,440
Total noninterest expenses	33,592	28,184	105,458	83,339
Segment profit	20,747	15,505	59,080	43,522
Intersegment (revenues) expenses	0	0	0	0
Pre-tax segment profit after eliminations	$ 20,747	$ 15,505	$ 59,080	$ 43,522
% of segment pre-tax profit after eliminations	100.00%	100.00%	100.00%	100.00%
Segment assets	$ 4,388,442	$ 3,476,800	$ 4,388,442	$ 3,476,800	$ 4,449,720
Assets under management, administration, supervision and brokerage	13,913,300		13,913,300		$ 12,968,700
Banking
Segment Reporting Information [Line Items]
Net interest income	36,726	29,437	111,479	84,804
Provision for loan and lease losses	664	1,333	4,831	1,541
Net interest income after provision for loan and lease losses	36,062	28,104	106,648	83,263
Fees for wealth management services	0	0	0	0
Insurance commissions	0	0	0	0
Capital markets revenue	710	843	3,481	1,796
Service charges on deposit accounts	726	676	2,191	1,953
Loan servicing and other fees	559	548	1,720	1,570
Net gain on sale of loans	631	799	1,677	1,948
Net gain on sale of investment securities available for sale			7	73
Net gain on sale of OREO	5	0	292	(12)
Other operating income	3,498	1,581	11,709	4,290
Total noninterest income	6,129	4,519	21,077	11,618
Salaries and wages	11,737	9,130	34,077	27,044
Employee benefits	2,394	1,587	6,992	4,565
Occupancy and bank premises	2,224	2,049	7,035	6,025
Amortization of intangible assets	386	197	1,169	588
Professional fees	889	681	2,497	2,318
Other operating expenses	7,770	6,970	29,076	21,200
Total noninterest expenses	25,400	20,614	80,846	61,740
Segment profit	16,791	12,009	46,879	33,141
Intersegment (revenues) expenses	(186)	(112)	(485)	(336)
Pre-tax segment profit after eliminations	$ 16,605	$ 11,897	$ 46,394	$ 32,805
% of segment pre-tax profit after eliminations	80.00%	76.70%	78.50%	75.40%
Segment assets	$ 4,335,800	$ 3,424,800	$ 4,335,800	$ 3,424,800
Wealth Management
Segment Reporting Information [Line Items]
Net interest income	3	1	5	2
Provision for loan and lease losses	0	0	0	0
Net interest income after provision for loan and lease losses	3	1	5	2
Fees for wealth management services	10,343	9,651	31,309	28,761
Insurance commissions	1,754	1,373	5,349	3,079
Capital markets revenue	0	0	0	0
Service charges on deposit accounts	0	0	0	0
Loan servicing and other fees	0	0	0	0
Net gain on sale of loans	0	0	0	0
Net gain on sale of investment securities available for sale			0	0
Net gain on sale of OREO	0	0	0	0
Other operating income	48	41	150	138
Total noninterest income	12,145	11,065	36,808	31,978
Salaries and wages	4,791	4,472	14,673	12,588
Employee benefits	962	973	2,949	2,888
Occupancy and bank premises	493	436	1,429	1,233
Amortization of intangible assets	505	480	1,490	1,469
Professional fees	108	58	180	181
Other operating expenses	1,333	1,151	3,891	3,240
Total noninterest expenses	8,192	7,570	24,612	21,599
Segment profit	3,956	3,496	12,201	10,381
Intersegment (revenues) expenses	186	112	485	336
Pre-tax segment profit after eliminations	$ 4,142	$ 3,608	$ 12,686	$ 10,717
% of segment pre-tax profit after eliminations	20.00%	23.30%	21.50%	24.60%
Segment assets	$ 52,600	$ 52,000	$ 52,600	$ 52,000