Loans and Allowance for Loan Losses - Nonaccrual loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	$ 18,854	$ 15,279	$ 18,854	$ 15,279	$ 14,827
Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	57,940	57,156	57,940	57,156	59,460
Recorded Investment With No Allowance	12,844	10,747	12,844	10,747	10,714
Gross Recorded Investment With Allowance	42,023	43,893	42,023	43,893	46,304
Total Recorded Investment	54,867	54,640	54,867	54,640	57,018
Related Allowance	1,221	1,657	1,221	1,657	1,628
Average Investment In Impaired Loans	54,688	58,617	55,943	59,032
Interest Income Recognized	516	346	1,769	1,593
Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	9,596	10,798	9,596	10,798	13,489
Commercial non-owner occupied real estate | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	869	1,514	869	1,514	1,255
Commercial non-owner occupied real estate | Non acquired non-accrual loans | Construction and land development
Loans and Allowance for Loan Losses
Nonaccrual loans	412	404	412	404	424
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	457	1,110	457	1,110	831
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	33,063	36,203	33,063	36,203	38,314
Recorded Investment With No Allowance	225	1,029	225	1,029	339
Gross Recorded Investment With Allowance	32,448	34,747	32,448	34,747	37,574
Total Recorded Investment	32,673	35,776	32,673	35,776	37,913
Related Allowance	587	723	587	723	788
Average Investment In Impaired Loans	34,401	39,084	35,293	39,503
Interest Income Recognized	177	158	967	968
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	146	1,480	146	1,480	1,157
Recorded Investment With No Allowance	74	812	74	812	536
Gross Recorded Investment With Allowance	13	503	13	503	489
Total Recorded Investment	87	1,315	87	1,315	1,025
Related Allowance		81		81	70
Average Investment In Impaired Loans	94	1,332	556	1,345
Interest Income Recognized	1	5	6	19
Commercial non-owner occupied real estate | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,297	402	1,297	402	535
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	1,031	402	1,031	402	252
Commercial non-owner occupied real estate | Acquired non-credit impaired non-accrual including restructured loans | Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Nonaccrual loans	266		266		283
Commercial owner occupied real estate loan | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	4,062	1,063	4,062	1,063	1,068
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	8,401	5,507	8,401	5,507	5,085
Recorded Investment With No Allowance	5,544	2,668	5,544	2,668	3,101
Gross Recorded Investment With Allowance	1,591	1,883	1,591	1,883	1,041
Total Recorded Investment	7,135	4,551	7,135	4,551	4,142
Related Allowance	33	40	33	40	27
Average Investment In Impaired Loans	6,288	4,650	5,638	5,096
Interest Income Recognized	129	81	290	228
Commercial owner occupied real estate loan | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	933	904	933	904	1,470
Consumer loans | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	8,647	9,029	8,647	9,029	9,442
Consumer loans | Non acquired non-accrual loans | Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,273	2,623	1,273	2,623	2,333
Consumer loans | Non acquired non-accrual loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	7,374	6,406	7,374	6,406	7,109
Consumer loans | 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	2,476	3,141	2,476	3,141	2,953
Recorded Investment With No Allowance	1,087	1,135	1,087	1,135	1,129
Gross Recorded Investment With Allowance	1,258	1,891	1,258	1,891	1,697
Total Recorded Investment	2,345	3,026	2,345	3,026	2,826
Related Allowance	121	171	121	171	142
Average Investment In Impaired Loans	2,391	3,085	2,586	3,019
Interest Income Recognized	36	30	100	95
Consumer loans | 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	5,441	5,914	5,441	5,914	7,291
Recorded Investment With No Allowance	3,610	4,478	3,610	4,478	4,992
Gross Recorded Investment With Allowance	1,517	942	1,517	942	1,769
Total Recorded Investment	5,127	5,420	5,127	5,420	6,761
Related Allowance	33	28	33	28	41
Average Investment In Impaired Loans	5,346	5,524	5,944	5,527
Interest Income Recognized	36	32	129	120
Consumer loans | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	4,773	7,309	4,773	7,309	8,376
Consumer loans | Acquired non-credit impaired non-accrual including restructured loans | Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	3,034	4,901	3,034	4,901	4,512
Consumer loans | Acquired non-credit impaired non-accrual including restructured loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,739	2,408	1,739	2,408	3,864
Commercial and industrial | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	2,565	957	2,565	957	647
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	5,779	1,462	5,779	1,462	1,332
Recorded Investment With No Allowance	1,874	467	1,874	467	467
Gross Recorded Investment With Allowance	3,439	942	3,439	942	824
Total Recorded Investment	5,313	1,409	5,313	1,409	1,291
Related Allowance	387	475	387	475	416
Average Investment In Impaired Loans	3,993	1,622	3,302	1,282
Interest Income Recognized	123	8	209	43
Commercial and industrial | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	692	354	692	354	1,296
Other income producing property | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	628	474	628	474	500
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	2,489	3,165	2,489	3,165	3,117
Recorded Investment With No Allowance	430	158	430	158	150
Gross Recorded Investment With Allowance	1,666	2,772	1,666	2,772	2,722
Total Recorded Investment	2,096	2,930	2,096	2,930	2,872
Related Allowance	58	133	58	133	142
Average Investment In Impaired Loans	2,080	3,085	2,484	3,034
Interest Income Recognized	14	32	68	120
Other income producing property | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	270	249	270	249	244
Consumer | Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,539	1,177	1,539	1,177	1,267
Consumer | Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	145	284	145	284	211
Gross Recorded Investment With Allowance	91	213	91	213	188
Total Recorded Investment	91	213	91	213	188
Related Allowance	2	6	2	6	2
Average Investment In Impaired Loans	95	235	140	226
Consumer | Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,631	1,580	$ 1,631	1,580	1,568
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	$ 544	$ 1,065	$ 544	$ 1,065	$ 648