Loans - Risk Categories of Loans by Class of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 198,892
2019	1,000,429
2018	935,256
2017	765,483
2016	688,535
Prior	1,094,810
Revolving	633,803
Total	5,317,208	$ 5,198,404
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	198,410
2019	995,300
2018	923,588
2017	747,503
2016	662,233
Prior	1,043,169
Revolving	620,625
Total	5,190,828	5,091,691
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	482
2019	3,540
2018	9,303
2017	5,940
2016	21,463
Prior	17,039
Revolving	4,316
Total	62,083	51,560
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	346
2018	167
2017	8,212
2016	2,358
Prior	12,920
Revolving	5,908
Total	29,911	53,958
Substandard Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	725
2018	1,224
2017	3,535
2016	1,824
Prior	21,682
Revolving	2,945
Total	31,935
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	518
2018	974
2017	293
2016	657
Prior	0
Revolving	9
Total	2,451	1,195
Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
2020	12,738
2019	94,799
2018	88,607
2017	37,337
2016	11,252
Prior	20,939
Revolving	29,733
Total	295,405	325,113
Construction and land development | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	12,458
2019	94,108
2018	87,137
2017	37,337
2016	10,678
Prior	18,562
Revolving	29,733
Total	290,013	317,765
Construction and land development | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	280
2019	691
2018	1,470
2017	0
2016	0
Prior	2,191
Revolving	0
Total	4,632	2,235
Construction and land development | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	32
Revolving	0
Total	32	5,113
Construction and land development | Substandard Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	574
Prior	154
Revolving	0
Total	728
Construction and land development | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Total	0	0
Commercial real estate - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
2020	43,090
2019	191,052
2018	162,955
2017	150,724
2016	166,992
Prior	351,069
Revolving	17,011
Total	1,082,893
Commercial real estate - owner occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	42,888
2019	189,419
2018	162,584
2017	145,468
2016	161,131
Prior	339,852
Revolving	17,011
Total	1,058,353
Commercial real estate - owner occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	202
2019	1,633
2018	371
2017	0
2016	4,471
Prior	5,147
Revolving	0
Total	11,824
Commercial real estate - owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	3,805
2016	1,070
Prior	3,335
Revolving	0
Total	8,210
Commercial real estate - owner occupied | Substandard Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	1,451
2016	0
Prior	2,735
Revolving	0
Total	4,186
Commercial real estate - owner occupied | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	320
Prior	0
Revolving	0
Total	320
Commercial real estate - non owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
2020	48,094
2019	328,545
2018	234,828
2017	136,697
2016	218,589
Prior	407,500
Revolving	6,843
Total	1,381,096
Commercial real estate - non owner occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	48,094
2019	328,437
2018	229,350
2017	131,409
2016	202,980
Prior	390,699
Revolving	5,493
Total	1,336,462
Commercial real estate - non owner occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	108
2018	5,478
2017	5,288
2016	15,483
Prior	6,529
Revolving	0
Total	32,886
Commercial real estate - non owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	5,345
Revolving	1,350
Total	6,695
Commercial real estate - non owner occupied | Substandard Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	126
Prior	4,927
Revolving	0
Total	5,053
Commercial real estate - non owner occupied | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Total	0
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total		2,378,971
Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total		2,331,725
Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total		26,827
Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total		20,098
Commercial real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total		321
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	33,704
2019	165,633
2018	282,880
2017	310,781
2016	210,981
Prior	237,911
Revolving	317,864
Total	1,559,754	1,507,863
Residential real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	33,704
2019	164,901
2018	281,466
2017	307,018
2016	209,956
Prior	223,116
Revolving	313,101
Total	1,533,262	1,482,278
Residential real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	25
2018	1,414
2017	0
2016	1,025
Prior	570
Revolving	805
Total	3,839	7,364
Residential real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	3,763
2016	0
Prior	2,235
Revolving	1,945
Total	7,943	18,221
Residential real estate | Substandard Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	707
2018	0
2017	0
2016	0
Prior	11,990
Revolving	2,013
Total	14,710
Residential real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Total	0	0
Commercial and financial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	48,507
2019	160,206
2018	122,838
2017	101,183
2016	51,748
Prior	62,463
Revolving	249,093
Total	796,038	778,252
Commercial and financial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	48,507
2019	158,373
2018	120,271
2017	97,771
2016	49,293
Prior	56,869
Revolving	244,912
Total	775,996	755,957
Commercial and financial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1,005
2018	263
2017	530
2016	363
Prior	2,505
Revolving	889
Total	5,555	11,925
Commercial and financial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	310
2018	106
2017	513
2016	675
Prior	1,922
Revolving	2,351
Total	5,877	9,496
Commercial and financial | Substandard Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	1,224
2017	2,076
2016	1,080
Prior	1,167
Revolving	932
Total	6,479
Commercial and financial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	518
2018	974
2017	293
2016	337
Prior	0
Revolving	9
Total	2,131	874
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	12,759
2019	60,194
2018	43,148
2017	28,761
2016	28,973
Prior	14,928
Revolving	13,259
Total	202,022	208,205
Consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	12,759
2019	60,062
2018	42,780
2017	28,500
2016	28,195
Prior	14,071
Revolving	10,375
Total	196,742	203,966
Consumer | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	78
2018	307
2017	122
2016	121
Prior	97
Revolving	2,622
Total	3,347	3,209
Consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	36
2018	61
2017	131
2016	613
Prior	51
Revolving	262
Total	1,154	1,030
Consumer | Substandard Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	18
2018	0
2017	8
2016	44
Prior	709
Revolving	0
Total	779
Consumer | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Total	$ 0	$ 0