Loans - Loan Delinquency (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Loans [Line Items]
Total loans	$ 4,246,941	$ 4,092,308	$ 3,702,334
Commercial Loan [Member]
Loans [Line Items]
Total loans	2,756,144	2,644,571
Commercial Real Estate [Member]
Loans [Line Items]
Total loans	645,954	592,212
Residential Real Estate Segment [Member]
Loans [Line Items]
Total loans	822,652	830,815
Consumer [Member]
Loans [Line Items]
Total loans	22,191	24,710
Originated and acquired loans [Member]
Loans [Line Items]
Total loans	4,183,414	4,021,429
Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Total loans	2,737,005	2,624,173
Originated and acquired loans [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Total loans	609,076	551,819
Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total loans	815,144	820,820
Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Total loans	22,189	24,617
ASC 310-30 [Member]
Loans [Line Items]
Total loans	63,527	70,879	$ 112,309
ASC 310-30 [Member] | Commercial Loan [Member]
Loans [Line Items]
Total loans	19,139	20,398
ASC 310-30 [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Total loans	36,878	40,393
ASC 310-30 [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total loans	7,508	9,995
ASC 310-30 [Member] | Consumer [Member]
Loans [Line Items]
Total loans	2	93
Total Loans [Member]
Loans [Line Items]
Total loans	4,246,941	4,092,308
Total Loans [Member] | Originated and acquired loans [Member]
Loans [Line Items]
Non- accrual	26,310	24,456
Total past due and non-accrual	33,914	29,961
Current	4,149,500	3,991,468
Total loans	4,183,414	4,021,429
Total Loans [Member] | Originated and acquired loans [Member] | Commercial Construction [Member]
Loans [Line Items]
Non- accrual	1,208	1,208
Total past due and non-accrual	1,563	1,208
Current	92,767	93,646
Total loans	94,330	94,854
Total Loans [Member] | Originated and acquired loans [Member] | Commercial Acquisition/Development [Member]
Loans [Line Items]
Non- accrual	115	121
Total past due and non-accrual	875	121
Current	17,493	19,529
Total loans	18,368	19,650
Total Loans [Member] | Originated and acquired loans [Member] | Multifamily [Member]
Loans [Line Items]
Current	60,635	56,685
Total loans	60,635	56,685
Total Loans [Member] | Originated and acquired loans [Member] | Commercial and Industrial [Member]
Loans [Line Items]
Non- accrual	6,136	5,510
Total past due and non-accrual	9,537	6,079
Current	2,010,349	1,925,068
Total loans	2,019,886	1,931,147
Total Loans [Member] | Originated and acquired loans [Member] | Owner-Occupied [Member]
Loans [Line Items]
Non- accrual	6,710	6,931
Total past due and non-accrual	7,364	7,824
Current	421,359	413,842
Total loans	428,723	421,666
Total Loans [Member] | Originated and acquired loans [Member] | Non Owner-Occupied [Member]
Loans [Line Items]
Non- accrual	897	572
Total past due and non-accrual	1,096	1,032
Current	434,647	379,598
Total loans	435,743	380,630
Total Loans [Member] | Originated and acquired loans [Member] | Total Commercial Real Estate [Member]
Loans [Line Items]
Non- accrual	2,220	1,901
Total past due and non-accrual	3,534	2,361
Current	605,542	549,458
Total loans	609,076	551,819
Total Loans [Member] | Originated and acquired loans [Member] | Senior lien
Loans [Line Items]
Non- accrual	8,768	7,790
Total past due and non-accrual	10,257	10,444
Current	707,162	712,592
Total loans	717,419	723,036
Total Loans [Member] | Originated and acquired loans [Member] | Junior lien
Loans [Line Items]
Non- accrual	832	772
Total past due and non-accrual	1,248	1,328
Current	96,477	96,456
Total loans	97,725	97,784
Total Loans [Member] | Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Non- accrual	14,409	13,951
Total past due and non-accrual	18,752	15,679
Current	2,718,253	2,608,494
Total loans	2,737,005	2,624,173
Total Loans [Member] | Originated and acquired loans [Member] | Food and Agriculture [Member]
Loans [Line Items]
Non- accrual	759	768
Total past due and non-accrual	1,047	1,034
Current	231,981	221,122
Total loans	233,028	222,156
Total Loans [Member] | Originated and acquired loans [Member] | Energy Loans [Member]
Loans [Line Items]
Non- accrual	804	742
Total past due and non-accrual	804	742
Current	54,564	48,462
Total loans	55,368	49,204
Total Loans [Member] | Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Non- accrual	9,600	8,562
Total past due and non-accrual	11,505	11,772
Current	803,639	809,048
Total loans	815,144	820,820
Total Loans [Member] | Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Non- accrual	81	42
Total past due and non-accrual	123	149
Current	22,066	24,468
Total loans	22,189	24,617
Total Loans [Member] | ASC 310-30 [Member]
Loans [Line Items]
Total loans	63,527	70,879
Total Loans [Member] | ASC 310-30 [Member] | Commercial Loan [Member]
Loans [Line Items]
Total loans	19,139	20,398
Total Loans [Member] | ASC 310-30 [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Total loans	36,878	40,393
Total Loans [Member] | ASC 310-30 [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total loans	7,508	9,990
Total Loans [Member] | ASC 310-30 [Member] | Consumer [Member]
Loans [Line Items]
Total loans	2	98
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member]
Loans [Line Items]
Past due loans	6,245	4,610
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Commercial Construction [Member]
Loans [Line Items]
Past due loans	355
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Commercial Acquisition/Development [Member]
Loans [Line Items]
Past due loans	35
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Commercial and Industrial [Member]
Loans [Line Items]
Past due loans	3,388	495
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Owner-Occupied [Member]
Loans [Line Items]
Past due loans	124	893
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Non Owner-Occupied [Member]
Loans [Line Items]
Past due loans	199	328
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Total Commercial Real Estate [Member]
Loans [Line Items]
Past due loans	589	328
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Senior lien
Loans [Line Items]
Past due loans	1,398	2,106
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Junior lien
Loans [Line Items]
Past due loans	416	556
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Past due loans	3,800	1,529
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Food and Agriculture [Member]
Loans [Line Items]
Past due loans	288	141
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Past due loans	1,814	2,662
Total Loans [Member] | 30-59 Days Past Due | Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Past due loans	42	91
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member]
Loans [Line Items]
Past due loans	1,359	895
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Commercial Acquisition/Development [Member]
Loans [Line Items]
Past due loans	725
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Commercial and Industrial [Member]
Loans [Line Items]
Past due loans	13	74
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Owner-Occupied [Member]
Loans [Line Items]
Past due loans	530
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Non Owner-Occupied [Member]
Loans [Line Items]
Past due loans		132
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Total Commercial Real Estate [Member]
Loans [Line Items]
Past due loans	725	132
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Senior lien
Loans [Line Items]
Past due loans	91	548
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Commercial Loan [Member]
Loans [Line Items]
Past due loans	543	199
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Food and Agriculture [Member]
Loans [Line Items]
Past due loans		125
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Past due loans	91	548
Total Loans [Member] | Greater than 90 Days Past Due | Originated and acquired loans [Member] | Consumer [Member]
Loans [Line Items]
Past due loans		$ 16
Non Accrual [Member]
Loans [Line Items]
Non- accrual	$ 26,300