Loans and Allowance for Loan Losses - Nonaccrual loans - (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	$ 14,760	$ 13,067	$ 14,760	$ 13,067	$ 14,340
Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	65,208	63,601	65,208	63,601	77,648
Recorded Investment With No Allowance	11,197	7,810	11,197	7,810	10,985
Gross Recorded Investment With Allowance	51,396	41,310	51,396	41,310	52,438
Total Recorded Investment	62,593	49,120	62,593	49,120	63,423
Related Allowance	1,829	2,300	1,829	2,300	1,624
Average Investment In Impaired Loans	64,645	38,221	63,008	35,165
Interest Income Recognized	520	478	1,248	719
Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	9,373	5,134	9,373	5,134	9,397
Commercial non-owner occupied real estate | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,532	2,637	1,532	2,637	2,886
Commercial non-owner occupied real estate | Non acquired non-accrual loans | Construction and land development
Loans and Allowance for Loan Losses
Nonaccrual loans	423	62	423	62	251
Commercial non-owner occupied real estate | Non acquired non-accrual loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Nonaccrual loans	1,109	2,575	1,109	2,575	2,635
Commercial non-owner occupied real estate | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 | Construction and land development
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	42,955	34,757	42,955	34,757	47,553
Recorded Investment With No Allowance	600	1,289	600	1,289	649
Gross Recorded Investment With Allowance	41,792	28,748	41,792	28,748	42,581
Total Recorded Investment	42,392	30,037	42,392	30,037	43,230
Related Allowance	846	1,310	846	1,310	1,063
Average Investment In Impaired Loans	44,295	19,662	42,811	16,535
Interest Income Recognized	298	267	810	314
Commercial non-owner occupied real estate | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	1,505	2,376	1,505	2,376	3,106
Recorded Investment With No Allowance	831	212	831	212	860
Gross Recorded Investment With Allowance	517	542	517	542	515
Total Recorded Investment	1,348	754	1,348	754	1,375
Related Allowance	93	146	93	146	125
Average Investment In Impaired Loans	1,265	764	1,362	780
Interest Income Recognized	9	6	15	12
Commercial non-owner occupied real estate | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	369	226	369	226	108
Commercial non-owner occupied real estate | Acquired non-credit impaired non-accrual including restructured loans | Construction and land development
Loans and Allowance for Loan Losses
Nonaccrual loans	369	226	369	226	108
Commercial owner occupied real estate loan | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,526	2,641	1,526	2,641	1,144
Commercial owner occupied real estate loan | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	5,733	9,882	5,733	9,882	9,212
Recorded Investment With No Allowance	3,031	4,075	3,031	4,075	3,553
Gross Recorded Investment With Allowance	1,719	1,979	1,719	1,979	2,089
Total Recorded Investment	4,750	6,054	4,750	6,054	5,642
Related Allowance	44	62	44	62	64
Average Investment In Impaired Loans	5,164	6,153	5,196	6,150
Interest Income Recognized	72	69	147	145
Commercial owner occupied real estate loan | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	885	44	885	44	189
Consumer real estate | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	8,773	4,166	8,773	4,166	5,157
Consumer real estate | Non acquired non-accrual loans | Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	2,308	10	2,308	10	269
Consumer real estate | Non acquired non-accrual loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	6,465	4,156	6,465	4,156	4,888
Consumer real estate | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Average Investment In Impaired Loans			248	189
Interest Income Recognized				3
Consumer real estate | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 | Home equity loans
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	3,256	3,311	3,256	3,311	3,602
Recorded Investment With No Allowance	1,146	688	1,146	688	896
Gross Recorded Investment With Allowance	1,998	1,938	1,998	1,938	2,115
Total Recorded Investment	3,144	2,626	3,144	2,626	3,011
Related Allowance	180	119	180	119	135
Average Investment In Impaired Loans	3,156	2,529	3,077	2,150
Interest Income Recognized	36	26	65	46
Consumer real estate | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	6,085	6,093	6,085	6,093	7,382
Recorded Investment With No Allowance	4,631	1,451	4,631	1,451	4,392
Gross Recorded Investment With Allowance	997	3,124	997	3,124	1,240
Total Recorded Investment	5,628	4,575	5,628	4,575	5,632
Related Allowance	30	57	30	57	37
Average Investment In Impaired Loans	5,561	4,644	5,630	5,124
Interest Income Recognized	44	35	87	74
Consumer real estate | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	6,370	3,442	6,370	3,442	6,745
Consumer real estate | Acquired non-credit impaired non-accrual including restructured loans | Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	4,234	1,515	4,234	1,515	4,589
Consumer real estate | Acquired non-credit impaired non-accrual including restructured loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	2,136	1,927	2,136	1,927	2,156
Commercial and industrial | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	811	596	811	596	1,662
Commercial and industrial | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	1,876	2,244	1,876	2,244	2,246
Recorded Investment With No Allowance	724		724		635
Gross Recorded Investment With Allowance	1,110	1,198	1,110	1,198	521
Total Recorded Investment	1,834	1,198	1,834	1,198	1,156
Related Allowance	485	362	485	362	15
Average Investment In Impaired Loans	1,756	1,234	1,495	1,230
Interest Income Recognized	19	4	36	22
Commercial and industrial | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	101	57	101	57	133
Other income producing property | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	323	1,162	323	1,162	764
Other income producing property | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	3,473	4,382	3,473	4,382	3,893
Recorded Investment With No Allowance	234	95	234	95
Gross Recorded Investment With Allowance	3,006	3,546	3,006	3,546	3,138
Total Recorded Investment	3,240	3,641	3,240	3,641	3,138
Related Allowance	144	238	144	238	178
Average Investment In Impaired Loans	3,163	3,024	3,189	3,007
Interest Income Recognized	42	68	88	103
Other income producing property | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	254	159	254	159	316
Consumer | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	893	898	893	898	1,802
Consumer | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	325	556	325	556	654
Gross Recorded Investment With Allowance	257	235	257	235	239
Total Recorded Investment	257	235	257	235	239
Related Allowance	7	6	7	6	7
Average Investment In Impaired Loans	285	211
Interest Income Recognized		3
Consumer | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,394	1,206	$ 1,394	1,206	1,906
Restructured loans | ASC Topic 31020 Loans
Loans and Allowance for Loan Losses
Number of months generally required to return to accruing status			6 months
Restructured loans | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	$ 902	$ 967	$ 902	$ 967	$ 925