Loans and Allowance for Loan Losses - Aging analysis of past due loans - (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Non-acquired loans
Loans and Allowance for Loan Losses
Past due	$ 15,345	$ 15,668
Current	5,225,696	4,205,058
Total loans	5,241,041	4,220,726	$ 3,467,826
Non-acquired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	6,223	5,674
Non-acquired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	3,302	2,650
Non-acquired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	5,820	7,344
Acquired credit impaired loans
Loans and Allowance for Loan Losses
Past due	24,066	29,912
Current	581,875	707,664
Acquired credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	6,887	8,635
Acquired credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	2,356	2,465
Acquired credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	14,823	18,812
Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Past due	4,484	4,924
Current	832,215	1,044,614
Total loans	836,699	1,049,538	1,327,999
Acquired non-credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,380	1,969
Acquired non-credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,265	884
Acquired non-credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,839	2,071
Residential real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Past due	12,570	13,955
Current	245,530	299,364
Residential real estate | Acquired credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	4,688	4,705
Residential real estate | Acquired credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,105	1,155
Residential real estate | Acquired credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	6,777	8,095
Commercial non-owner occupied real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,295,179	889,756
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development
Loans and Allowance for Loan Losses
Past due	1,595	1,374
Current	578,869	400,605
Total loans	580,464	401,979	364,221
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	256	323
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	313	136
Commercial non-owner occupied real estate | Non-acquired loans | Construction and land development | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,026	915
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Past due	1,016	1,051
Current	713,699	486,726
Total loans	714,715	487,777	333,590
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	647	867
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	232
Commercial non-owner occupied real estate | Non-acquired loans | Other commercial non-owner occupied real estate | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	137	184
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Past due	4,269	3,313
Current	40,104	50,959
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	168	784
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	489	367
Commercial non-owner occupied real estate | Acquired credit impaired loans | Construction and land development | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	3,612	2,162
Commercial non-owner occupied real estate | Acquired credit impaired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Past due	3,597	7,168
Current	206,607	248,262
Commercial non-owner occupied real estate | Acquired credit impaired loans | Other commercial non-owner occupied real estate | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	573	1,118
Commercial non-owner occupied real estate | Acquired credit impaired loans | Other commercial non-owner occupied real estate | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	357	426
Commercial non-owner occupied real estate | Acquired credit impaired loans | Other commercial non-owner occupied real estate | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	2,667	5,624
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development
Loans and Allowance for Loan Losses
Past due	164	69
Current	9,926	13,780
Total loans	10,090	13,849	24,099
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	4
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		21
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Construction and land development | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	160	48
Commercial non-owner occupied real estate | Acquired non-credit impaired loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Current	34,628	40,103
Total loans	34,628	40,103	49,476
Commercial owner occupied real estate loan | Non-acquired loans
Loans and Allowance for Loan Losses
Past due	3,707	3,407
Current	1,174,038	1,029,991
Total loans	1,177,745	1,033,398	907,913
Commercial owner occupied real estate loan | Non-acquired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,272	1,269
Commercial owner occupied real estate loan | Non-acquired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	957	608
Commercial owner occupied real estate loan | Non-acquired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,478	1,530
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Past due	106	340
Current	27,089	38,880
Total loans	27,195	39,220	62,065
Commercial owner occupied real estate loan | Acquired non-credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		120
Commercial owner occupied real estate loan | Acquired non-credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		176
Commercial owner occupied real estate loan | Acquired non-credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	106	44
Consumer real estate | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	1,580,839	1,338,239
Consumer real estate | Non-acquired loans | Home equity loans
Loans and Allowance for Loan Losses
Past due	2,293	2,543
Current	380,925	316,712
Total loans	383,218	319,255	283,934
Consumer real estate | Non-acquired loans | Home equity loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	566	899
Consumer real estate | Non-acquired loans | Home equity loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	889	1,046
Consumer real estate | Non-acquired loans | Home equity loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	838	598
Consumer real estate | Non-acquired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Past due	3,173	4,960
Current	1,194,448	1,014,024
Total loans	1,197,621	1,018,984	786,778
Consumer real estate | Non-acquired loans | Consumer Owner Occupied Loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,473	1,503
Consumer real estate | Non-acquired loans | Consumer Owner Occupied Loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	246	308
Consumer real estate | Non-acquired loans | Consumer Owner Occupied Loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,454	3,149
Consumer real estate | Non-acquired loans | Other Consumer
Loans and Allowance for Loan Losses
Total loans	13,404	46,573
Consumer real estate | Acquired non-credit impaired loans | Home equity loans
Loans and Allowance for Loan Losses
Past due	2,158	1,791
Current	158,721	189,177
Total loans	160,879	190,968	234,949
Consumer real estate | Acquired non-credit impaired loans | Home equity loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	476	897
Consumer real estate | Acquired non-credit impaired loans | Home equity loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	941	412
Consumer real estate | Acquired non-credit impaired loans | Home equity loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	741	482
Consumer real estate | Acquired non-credit impaired loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Past due	699	1,386
Current	407,571	516,721
Total loans	408,270	518,107	646,375
Consumer real estate | Acquired non-credit impaired loans | Consumer Owner Occupied Loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	330	694
Consumer real estate | Acquired non-credit impaired loans | Consumer Owner Occupied Loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	113	4
Consumer real estate | Acquired non-credit impaired loans | Consumer Owner Occupied Loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	256	688
Commercial and industrial | Non-acquired loans
Loans and Allowance for Loan Losses
Past due	1,594	573
Current	669,804	503,235
Total loans	671,398	503,808	405,923
Commercial and industrial | Non-acquired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,033	173
Commercial and industrial | Non-acquired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	216	166
Commercial and industrial | Non-acquired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	345	234
Commercial and industrial | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Past due	606	1,255
Current	24,741	29,938
Commercial and industrial | Acquired credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	46	272
Commercial and industrial | Acquired credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	24	137
Commercial and industrial | Acquired credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	536	846
Commercial and industrial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Past due	2	7
Current	13,639	25,468
Total loans	13,641	25,475	41,130
Commercial and industrial | Acquired non-credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	2	1
Commercial and industrial | Acquired non-credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		1
Commercial and industrial | Acquired non-credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		5
Other income producing property | Non-acquired loans
Loans and Allowance for Loan Losses
Past due	551	723
Current	177,687	175,125
Total loans	178,238	175,848	150,928
Other income producing property | Non-acquired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	310	241
Other income producing property | Non-acquired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	94	207
Other income producing property | Non-acquired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	147	275
Other income producing property | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Past due	132	7
Current	39,210	51,162
Total loans	39,342	51,169	65,139
Other income producing property | Acquired non-credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	131
Other income producing property | Acquired non-credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1
Other income producing property | Acquired non-credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		7
Consumer | Non-acquired loans
Loans and Allowance for Loan Losses
Past due	1,416	882
Current	322,822	232,222
Total loans	324,238	233,104	189,317
Consumer | Non-acquired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	666	351
Consumer | Non-acquired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	355	136
Consumer | Non-acquired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	395	395
Consumer | Non-acquired loans | All Consumer
Loans and Allowance for Loan Losses
Total loans	1,918,481	1,617,916
Consumer | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Past due	3,024	4,221
Current	56,276	66,513
Consumer | Acquired credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,412	1,756
Consumer | Acquired credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	381	380
Consumer | Acquired credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	1,231	2,085
Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Past due	1,223	1,324
Current	141,431	169,323
Total loans	142,654	170,647	204,766
Consumer | Acquired non-credit impaired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	437	257
Consumer | Acquired non-credit impaired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	210	270
Consumer | Acquired non-credit impaired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due	576	797
Commercial | Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	3,322,560	2,602,810
Other loans | Non-acquired loans
Loans and Allowance for Loan Losses
Past due		155
Current	13,404	46,418
Total loans	13,404	46,573	$ 45,222
Other loans | Non-acquired loans | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		48
Other loans | Non-acquired loans | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		43
Other loans | Non-acquired loans | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans and Allowance for Loan Losses
Past due		64
Commercial loans 1000000 or more | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Current	$ 8,617	$ 12,628