Loans - (Loan Delinquency) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Loans [Line Items]
Total loans	$ 3,702,334	$ 3,178,947	$ 2,953,655
Commercial Loan [Member]
Loans [Line Items]
Total loans	2,105,899	1,874,605
Commercial Real Estate [Member]
Loans [Line Items]
Total loans	710,715	563,049
Residential Real Estate Segment [Member]
Loans [Line Items]
Total loans	859,155	716,237
Consumer [Member]
Loans [Line Items]
Total loans	26,565	25,056
Originated and acquired loans [Member]
Loans [Line Items]
Total loans	3,590,025	3,058,324
Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Total loans	2,081,197	1,845,130
Originated and acquired loans [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Total loans	635,438	485,141
Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total loans	847,155	703,478
Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Total loans	26,235	24,575
ASC 310-30 [Member]
Loans [Line Items]
Total loans	112,309	120,623	$ 140,064
ASC 310-30 [Member] | Commercial Loan [Member]
Loans [Line Items]
Total loans	24,702	29,475
ASC 310-30 [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Total loans	75,277	77,908
ASC 310-30 [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total loans	12,000	12,759
ASC 310-30 [Member] | Consumer [Member]
Loans [Line Items]
Total loans	330	481
Total Loans [Member]
Loans [Line Items]
Total loans	3,702,334	3,178,947
Total Loans [Member] | Originated and acquired loans [Member]
Loans [Line Items]
Total past due loans	16,130	13,557
Current	3,573,895	3,044,767
Total loans	3,590,025	3,058,324
Loans 90 days past due and still accruing	1,767	150
Non- accrual	23,669	21,000
Total Loans [Member] | Originated and acquired loans [Member] | Commercial Construction [Member]
Loans [Line Items]
Total past due loans	2,048	179
Current	110,038	107,502
Total loans	112,086	107,681
Loans 90 days past due and still accruing	642
Non- accrual		179
Total Loans [Member] | Originated and acquired loans [Member] | Commercial Acquisition/Development [Member]
Loans [Line Items]
Total past due loans	51	1,097
Current	23,058	13,318
Total loans	23,109	14,415
Loans 90 days past due and still accruing	51
Non- accrual	833
Total Loans [Member] | Originated and acquired loans [Member] | Multifamily [Member]
Loans [Line Items]
Total past due loans	29
Current	51,712	26,947
Total loans	51,741	26,947
Non- accrual	29
Total Loans [Member] | Originated and acquired loans [Member] | Commercial and Industrial [Member]
Loans [Line Items]
Total past due loans	2,413	2,060
Current	1,492,675	1,373,962
Total loans	1,495,088	1,376,022
Loans 90 days past due and still accruing	150	150
Non- accrual	5,302	7,767
Total Loans [Member] | Originated and acquired loans [Member] | Owner-Occupied [Member]
Loans [Line Items]
Total past due loans	3,764	2,679
Current	380,483	270,074
Total loans	384,247	272,753
Loans 90 days past due and still accruing	535
Non- accrual	7,202	3,478
Total Loans [Member] | Originated and acquired loans [Member] | Non Owner-Occupied [Member]
Loans [Line Items]
Total past due loans	10	630
Current	448,492	335,468
Total loans	448,502	336,098
Non- accrual	613	605
Total Loans [Member] | Originated and acquired loans [Member] | Total Commercial Real Estate [Member]
Loans [Line Items]
Total past due loans	2,138	1,906
Current	633,300	483,235
Total loans	635,438	485,141
Loans 90 days past due and still accruing	693
Non- accrual	1,475	784
Total Loans [Member] | Originated and acquired loans [Member] | Senior lien
Loans [Line Items]
Total past due loans	4,361	3,448
Current	744,083	643,034
Total loans	748,444	646,482
Loans 90 days past due and still accruing	238
Non- accrual	5,918	4,724
Total Loans [Member] | Originated and acquired loans [Member] | Junior lien
Loans [Line Items]
Total past due loans	1,280	365
Current	97,431	56,631
Total loans	98,711	56,996
Non- accrual	710	459
Total Loans [Member] | Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Total past due loans	7,985	7,670
Current	2,073,212	1,837,460
Total loans	2,081,197	1,845,130
Loans 90 days past due and still accruing	701	150
Non- accrual	15,530	14,893
Total Loans [Member] | Originated and acquired loans [Member] | Agriculture [Member]
Loans [Line Items]
Total past due loans	885	1,286
Current	160,764	137,609
Total loans	161,649	138,895
Loans 90 days past due and still accruing	16
Non- accrual	2,103	2,003
Total Loans [Member] | Originated and acquired loans [Member] | Energy Loans [Member]
Loans [Line Items]
Total past due loans	923	1,645
Current	39,290	55,815
Total loans	40,213	57,460
Non- accrual	923	1,645
Total Loans [Member] | Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total past due loans	5,641	3,813
Current	841,514	699,665
Total loans	847,155	703,478
Loans 90 days past due and still accruing	238
Non- accrual	6,628	5,183
Total Loans [Member] | Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Total past due loans	366	168
Current	25,869	24,407
Total loans	26,235	24,575
Loans 90 days past due and still accruing	135
Non- accrual	36	140
Total Loans [Member] | ASC 310-30 [Member]
Loans [Line Items]
Total loans	112,309	120,623
Total Loans [Member] | ASC 310-30 [Member] | Commercial Loan [Member]
Loans [Line Items]
Total loans	24,702	29,475
Total Loans [Member] | ASC 310-30 [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Total loans	75,277	77,908
Total Loans [Member] | ASC 310-30 [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total loans	12,000	12,759
Total Loans [Member] | ASC 310-30 [Member] | Consumer [Member]
Loans [Line Items]
Total loans	330	481
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member]
Loans [Line Items]
Total past due loans	5,880	4,545
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Commercial Construction [Member]
Loans [Line Items]
Total past due loans	465
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Commercial Acquisition/Development [Member]
Loans [Line Items]
Total past due loans		1,097
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Commercial and Industrial [Member]
Loans [Line Items]
Total past due loans	1,083	554
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Owner-Occupied [Member]
Loans [Line Items]
Total past due loans	440	696
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Non Owner-Occupied [Member]
Loans [Line Items]
Total past due loans		56
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Total Commercial Real Estate [Member]
Loans [Line Items]
Total past due loans	465	1,153
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Senior lien
Loans [Line Items]
Total past due loans	2,535	1,167
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Junior lien
Loans [Line Items]
Total past due loans	1,002	233
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Total past due loans	1,674	1,835
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Agriculture [Member]
Loans [Line Items]
Total past due loans	151	585
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total past due loans	3,537	1,400
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Total past due loans	204	157
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member]
Loans [Line Items]
Total past due loans	2,170	1,099
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Commercial Construction [Member]
Loans [Line Items]
Total past due loans	941
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Commercial and Industrial [Member]
Loans [Line Items]
Total past due loans	116	117
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Owner-Occupied [Member]
Loans [Line Items]
Total past due loans	534
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Non Owner-Occupied [Member]
Loans [Line Items]
Total past due loans	10
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Total Commercial Real Estate [Member]
Loans [Line Items]
Total past due loans	951
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Senior lien
Loans [Line Items]
Total past due loans	309	885
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Junior lien
Loans [Line Items]
Total past due loans	238	91
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Total past due loans	650	117
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total past due loans	547	976
Total Loans [Member] | 60-89 Days Past Due | Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Total past due loans	22	6
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member]
Loans [Line Items]
Total past due loans	8,080	7,913
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Commercial Construction [Member]
Loans [Line Items]
Total past due loans	642	179
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Commercial Acquisition/Development [Member]
Loans [Line Items]
Total past due loans	51
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Multifamily [Member]
Loans [Line Items]
Total past due loans	29
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Commercial and Industrial [Member]
Loans [Line Items]
Total past due loans	1,214	1,389
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Owner-Occupied [Member]
Loans [Line Items]
Total past due loans	2,790	1,983
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Non Owner-Occupied [Member]
Loans [Line Items]
Total past due loans		574
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Total Commercial Real Estate [Member]
Loans [Line Items]
Total past due loans	722	753
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Senior lien
Loans [Line Items]
Total past due loans	1,517	1,396
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Junior lien
Loans [Line Items]
Total past due loans	40	41
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Total past due loans	5,661	5,718
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Agriculture [Member]
Loans [Line Items]
Total past due loans	734	701
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Energy Loans [Member]
Loans [Line Items]
Total past due loans	923	1,645
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total past due loans	1,557	1,437
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Total past due loans	140	$ 5
Non Accrual [Member]
Loans [Line Items]
Non- accrual	$ 23,700