Loans and Allowance for Loan Losses - Nonaccrual loans - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	$ 12,367	$ 14,884	$ 12,367	$ 14,884	$ 14,464
Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	74,409	35,011	74,409	35,011	35,079
Recorded Investment With No Allowance	7,182	7,755	7,182	7,755	7,736
Gross Recorded Investment With Allowance	53,610	13,432	53,610	13,432	13,475
Total Recorded Investment	60,792	21,187	60,792	21,187	21,211
Related Allowance	1,862	1,379	1,862	1,379	1,337
Average Investment In Impaired Loans	54,955	22,755	41,002	25,702
Interest Income Recognized	677	312	1,396	653
Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	5,457	4,633	5,457	4,633	4,728
Commercial non-owner occupied real estate | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	2,812	1,757	2,812	1,757	1,250
Commercial non-owner occupied real estate | Non acquired non-accrual loans | Construction and land development
Loans and Allowance for Loan Losses
Nonaccrual loans	57	1,156	57	1,156	672
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	2,755	601	2,755	601	578
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	46,664	7,744	46,664	7,744	7,394
Recorded Investment With No Allowance	954	1,331	954	1,331	1,074
Gross Recorded Investment With Allowance	41,684	2,100	41,684	2,100	1,959
Total Recorded Investment	42,638	3,431	42,638	3,431	3,033
Related Allowance	1,266	359	1,266	359	348
Average Investment In Impaired Loans	36,337	3,762
Interest Income Recognized	486	31
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	2,361	2,372	2,361	2,372	2,417
Recorded Investment With No Allowance	207	228	207	228	223
Gross Recorded Investment With Allowance	509	536	509	536	583
Total Recorded Investment	716	764	716	764	806
Related Allowance	133	181	133	181	170
Average Investment In Impaired Loans	735	992
Interest Income Recognized	3
Commercial non-owner occupied real estate | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	233	235	233	235	232
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	233	235	233	235	232
Commercial owner occupied real estate loan | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	557	2,049	557	2,049	2,189
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	9,504	10,204	9,504	10,204	10,118
Recorded Investment With No Allowance	3,936	4,301	3,936	4,301	3,976
Gross Recorded Investment With Allowance	1,938	2,051	1,938	2,051	2,269
Total Recorded Investment	5,874	6,352	5,874	6,352	6,245
Related Allowance	64	65	64	65	67
Average Investment In Impaired Loans	5,964	6,662
Interest Income Recognized	63	150
Commercial owner occupied real estate loan | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans		302		302	61
Consumer real estate | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	3,982	6,612	3,982	6,612	7,340
Consumer real estate | Non acquired non-accrual loans | Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	308	1,564	308	1,564	1,629
Consumer real estate | Non acquired non-accrual loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	3,674	5,048	3,674	5,048	5,711
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	3,184	2,054	3,184	2,054	2,165
Recorded Investment With No Allowance	716	251	716	251	244
Gross Recorded Investment With Allowance	1,907	1,348	1,907	1,348	1,430
Total Recorded Investment	2,623	1,599	2,623	1,599	1,674
Related Allowance	116	38	116	38	40
Average Investment In Impaired Loans	2,624	1,888
Interest Income Recognized	29	13
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	5,986	4,390	5,986	4,390	7,090
Recorded Investment With No Allowance	1,369	1,284	1,369	1,284	2,120
Gross Recorded Investment With Allowance	3,086	1,843	3,086	1,843	3,553
Total Recorded Investment	4,455	3,127	4,455	3,127	5,673
Related Allowance	47	58	47	58	80
Average Investment In Impaired Loans	4,515	3,547
Interest Income Recognized	36	31
Consumer real estate | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	3,704	2,700	3,704	2,700	3,048
Consumer real estate | Acquired non-credit impaired non-accrual including restructured loans | Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,813	1,588	1,813	1,588	1,643
Consumer real estate | Acquired non-credit impaired non-accrual including restructured loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,891	1,112	1,891	1,112	1,405
Commercial and industrial | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,952	587	1,952	587	420
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	1,753	2,738	1,753	2,738	2,335
Recorded Investment With No Allowance		259		259
Gross Recorded Investment With Allowance	627	1,194	627	1,194	1,263
Total Recorded Investment	627	1,453	627	1,453	1,263
Related Allowance	18	385	18	385	386
Average Investment In Impaired Loans	912	1,110	945	1,470
Interest Income Recognized	8	16	30	28
Commercial and industrial | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	114	1	114	1	1
Other income producing property | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,083	584	1,083	584	356
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	4,334	5,167	4,334	5,167	3,166
Recorded Investment With No Allowance		101		101	99
Gross Recorded Investment With Allowance	3,605	4,218	3,605	4,218	2,273
Total Recorded Investment	3,605	4,319	3,605	4,319	2,372
Related Allowance	211	289	211	289	242
Average Investment In Impaired Loans	3,623	4,659	2,989	4,605
Interest Income Recognized	50	71	153	157
Other income producing property | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	107	149	107	149	145
Consumer | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,123	796	1,123	796	930
Consumer | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	623	342	623	342	394
Gross Recorded Investment With Allowance	254	142	254	142	145
Total Recorded Investment	254	142	254	142	145
Related Allowance	7	4	7	4	4
Average Investment In Impaired Loans	245	135	200	122
Interest Income Recognized	2		5	3
Consumer | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 | Home equity loans
Loans and Allowance for Loan Losses
Average Investment In Impaired Loans			2,148	954
Interest Income Recognized			75	43
Consumer | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Average Investment In Impaired Loans			5,064	5,338
Interest Income Recognized			110	78
Consumer | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,299	1,246	1,299	1,246	1,241
Commercial | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Average Investment In Impaired Loans			761	1,108
Interest Income Recognized			15	23
Commercial | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 | Construction and land development
Loans and Allowance for Loan Losses
Average Investment In Impaired Loans			22,835	4,856
Interest Income Recognized			800	88
Commercial | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Average Investment In Impaired Loans			6,060	7,038
Interest Income Recognized			$ 208	233
Other loans | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Average Investment In Impaired Loans				211
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	$ 858	$ 2,499	$ 858	$ 2,499	$ 1,979