Loans and Allowance for Loan Losses - Disaggregated analysis of activity in for allowances for non acquired loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for loan losses:
Charge-offs	$ (9,775)	$ (8,226)	$ (6,779)
Recoveries	3,914	3,300	3,430
Non-acquired loans
Allowance for loan losses:
Balance at beginning of period	51,194	43,448	36,960
Charge-offs	(6,917)	(6,012)	(5,149)
Recoveries	3,367	2,995	2,953
Provision (benefit)	9,283	10,763	8,684
Balance at end of period	56,927	51,194	43,448
Loans individually evaluated for impairment	1,346	1,628	1,624
Loans collectively evaluated for impairment	55,581	49,566	41,824
Loans:
Loans individually evaluated for impairment	58,532	57,018	63,423
Loans collectively evaluated for impairment	9,194,299	7,876,268	6,428,732
Total loans	9,252,831	7,933,286	6,492,155
Acquired non-credit impaired loans
Allowance for loan losses:
Charge-offs	(2,858)	(2,214)	(1,630)
Recoveries	547	305	477
Provision (benefit)	2,311	1,909	1,153
Loans:
Loans collectively evaluated for impairment	1,760,427	2,594,826	3,507,907
Total loans	1,760,427	2,594,826	3,507,907
Commercial non-owner occupied real estate | Non-acquired loans
Loans:
Total loans	2,779,498	2,256,996
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development
Allowance for loan losses:
Balance at beginning of period	5,682	5,921	4,091
Charge-offs	(78)	(76)	(546)
Recoveries	1,016	1,340	968
Provision (benefit)	(516)	(1,503)	1,408
Balance at end of period	6,104	5,682	5,921
Loans individually evaluated for impairment	617	788	1,063
Loans collectively evaluated for impairment	5,487	4,894	4,858
Loans:
Loans individually evaluated for impairment	35,201	37,913	43,230
Loans collectively evaluated for impairment	933,159	803,532	787,645
Total loans	968,360	841,445	830,875
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate
Allowance for loan losses:
Balance at beginning of period	8,754	6,525	4,980
Charge-offs	(3)
Recoveries	76	11	132
Provision (benefit)	1,872	2,218	1,413
Balance at end of period	10,699	8,754	6,525
Loans individually evaluated for impairment		70	125
Loans collectively evaluated for impairment	10,699	8,684	6,400
Loans:
Loans individually evaluated for impairment	379	1,025	1,375
Loans collectively evaluated for impairment	1,810,759	1,414,526	1,007,518
Total loans	1,811,138	1,415,551	1,008,893
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Other commercial non-owner occupied real estate
Loans:
Loans collectively evaluated for impairment	447,441	679,253	817,166
Total loans	447,441	679,253	817,166
Commercial owner occupied real estate loan | Non-acquired loans
Allowance for loan losses:
Balance at beginning of period	9,369	8,128	8,022
Charge-offs	(87)	(659)
Recoveries	174	145	220
Provision (benefit)	1,125	1,755	(114)
Balance at end of period	10,581	9,369	8,128
Loans individually evaluated for impairment	24	27	64
Loans collectively evaluated for impairment	10,557	9,342	8,064
Loans:
Loans individually evaluated for impairment	6,575	4,142	5,642
Loans collectively evaluated for impairment	1,777,442	1,513,409	1,257,134
Total loans	1,784,017	1,517,551	1,262,776
Consumer loans | Non-acquired loans
Loans:
Total loans	2,637,467	2,431,413
Consumer loans | Non-acquired loans | Home equity loans
Allowance for loan losses:
Balance at beginning of period	3,434	3,250	3,211
Charge-offs	(203)	(215)	(330)
Recoveries	265	279	210
Provision (benefit)	(308)	120	159
Balance at end of period	3,188	3,434	3,250
Loans individually evaluated for impairment	132	142	135
Loans collectively evaluated for impairment	3,056	3,292	3,115
Loans:
Loans individually evaluated for impairment	2,461	2,826	3,011
Loans collectively evaluated for impairment	516,167	492,322	434,631
Total loans	518,628	495,148	437,642
Consumer loans | Non-acquired loans | Other Consumer
Loans:
Total loans	13,892	9,357
Consumer loans | Non-acquired loans | Consumer Owner Occupied Loans
Allowance for loan losses:
Balance at beginning of period	11,913	9,668	7,820
Charge-offs	(50)	(80)	(185)
Recoveries	213	132	306
Provision (benefit)	520	2,193	1,727
Balance at end of period	12,596	11,913	9,668
Loans individually evaluated for impairment	102	41	37
Loans collectively evaluated for impairment	12,494	11,872	9,631
Loans:
Loans individually evaluated for impairment	5,141	6,761	5,632
Loans collectively evaluated for impairment	2,113,698	1,929,504	1,524,628
Total loans	2,118,839	1,936,265	1,530,260
Consumer loans | Acquired non-credit impaired loans | Home equity loans
Allowance for loan losses:
Charge-offs	(263)	(436)	(859)
Recoveries	206	102	393
Provision (benefit)	57	334	466
Loans:
Loans collectively evaluated for impairment	188,732	242,425	320,591
Total loans	188,732	242,425	320,591
Consumer loans | Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Allowance for loan losses:
Charge-offs	(6)	(70)	(150)
Recoveries	26	64	41
Provision (benefit)	(20)	6	109
Loans:
Loans collectively evaluated for impairment	496,431	628,813	710,611
Total loans	496,431	628,813	710,611
Commercial and industrial | Non-acquired loans
Allowance for loan losses:
Balance at beginning of period	7,454	5,488	4,842
Charge-offs	(622)	(500)	(776)
Recoveries	351	256	343
Provision (benefit)	1,156	2,210	1,079
Balance at end of period	8,339	7,454	5,488
Loans individually evaluated for impairment	366	416	15
Loans collectively evaluated for impairment	7,973	7,038	5,473
Loans:
Loans individually evaluated for impairment	6,578	1,291	1,156
Loans collectively evaluated for impairment	1,274,281	1,053,661	814,031
Total loans	1,280,859	1,054,952	815,187
Commercial and industrial | Acquired non-credit impaired loans
Allowance for loan losses:
Charge-offs	(1,289)	(1,108)	(71)
Recoveries	190	63	6
Provision (benefit)	1,099	1,045	65
Loans:
Loans collectively evaluated for impairment	101,880	212,537	398,696
Total loans	101,880	212,537	398,696
Other income producing property | Non-acquired loans
Allowance for loan losses:
Balance at beginning of period	1,446	1,375	1,542
Charge-offs	(31)	(2)	(51)
Recoveries	94	21	85
Provision (benefit)	(173)	52	(201)
Balance at end of period	1,336	1,446	1,375
Loans individually evaluated for impairment	50	142	178
Loans collectively evaluated for impairment	1,286	1,304	1,197
Loans:
Loans individually evaluated for impairment	2,024	2,872	3,138
Loans collectively evaluated for impairment	216,593	211,481	190,709
Total loans	218,617	214,353	193,847
Other income producing property | Acquired non-credit impaired loans
Allowance for loan losses:
Charge-offs	(26)
Recoveries	71		8
Provision (benefit)	(45)		(8)
Loans:
Loans collectively evaluated for impairment	95,697	133,110	196,669
Total loans	95,697	133,110	196,669
Consumer | Non-acquired loans
Allowance for loan losses:
Balance at beginning of period	3,101	2,788	2,350
Charge-offs	(5,843)	(4,480)	(3,261)
Recoveries	1,178	811	689
Provision (benefit)	5,511	3,982	3,010
Balance at end of period	3,947	3,101	2,788
Loans individually evaluated for impairment	55	2	7
Loans collectively evaluated for impairment	3,892	3,099	2,781
Loans:
Loans individually evaluated for impairment	173	188	239
Loans collectively evaluated for impairment	538,308	448,476	378,746
Total loans	538,481	448,664	378,985
Consumer | Acquired non-credit impaired loans
Allowance for loan losses:
Charge-offs	(444)	(465)	(468)
Recoveries	51	68	23
Provision (benefit)	393	397	445
Loans:
Loans collectively evaluated for impairment	89,484	111,777	137,710
Total loans	89,484	111,777	137,710
Commercial loans | Non-acquired loans
Loans:
Total loans	6,062,991	5,043,852
Commercial loans | Acquired non-credit impaired loans | Construction and land development
Allowance for loan losses:
Charge-offs	(44)	(107)	(82)
Recoveries	3	8	4
Provision (benefit)	41	99	78
Loans:
Loans collectively evaluated for impairment	33,569	165,070	403,357
Total loans	33,569	165,070	403,357
Commercial loans | Acquired non-credit impaired loans | Other commercial non-owner occupied real estate
Allowance for loan losses:
Charge-offs	(786)	(28)
Recoveries			2
Provision (benefit)	786	28	(2)
Loans:
Loans collectively evaluated for impairment	307,193	421,841	521,818
Total loans	307,193	421,841	521,818
Other loans
Loans:
Loans collectively evaluated for impairment			1,289
Total loans			1,289
Other loans | Non-acquired loans
Allowance for loan losses:
Balance at beginning of period	41	305	102
Provision (benefit)	96	(264)	203
Balance at end of period	137	41	305
Loans collectively evaluated for impairment	137	41	305
Loans:
Loans collectively evaluated for impairment	13,892	9,357	33,690
Total loans	$ 13,892	$ 9,357	$ 33,690