Non-performing Loans and Impaired Loans - Payment Status by Class of Loan (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Current	$ 3,673,395	$ 3,609,036
Total Past Due	12,263	7,875
Total	$ 3,685,658	$ 3,616,911
Current,Percentage of total loans	99.67%	99.78%
Total Past Due, Percentage of Total Loans	0.33%	0.22%
Percentage of total loans	100.00%	100.00%
Carrying Amount	$ 3,658,859
Commercial
Financing Receivable, Past Due [Line Items]
Current	2,033,507	$ 2,039,953
Total Past Due	7,466	1,830
Total	2,040,973	2,041,783
Commercial | Owner occupied real estate
Financing Receivable, Past Due [Line Items]
Current	499,639	515,604
Total Past Due	5,121	920
Total	504,760	516,524
Commercial | Non-owner occupied real estate
Financing Receivable, Past Due [Line Items]
Current	989,572	972,195
Total Past Due	2,021	80
Total	991,593	972,275
Commercial | Residential spec homes
Financing Receivable, Past Due [Line Items]
Current	11,533	12,925
Total Past Due	135	0
Total	11,668	12,925
Commercial | Development & spec land
Financing Receivable, Past Due [Line Items]
Current	32,918	35,881
Total Past Due	0	0
Total	32,918	35,881
Commercial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Current	499,845	503,348
Total Past Due	189	830
Total	500,034	504,178
Real estate
Financing Receivable, Past Due [Line Items]
Current	970,880	910,691
Total Past Due	1,395	1,985
Total	972,275	912,676
Real estate | Residential mortgage
Financing Receivable, Past Due [Line Items]
Current	722,866	740,712
Total Past Due	1,395	1,985
Total	724,261	742,697
Real estate | Residential construction
Financing Receivable, Past Due [Line Items]
Current	24,495	19,686
Total Past Due	0	0
Total	24,495	19,686
Real estate | Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Current	223,519	150,293
Total Past Due	0	0
Total	223,519	150,293
Consumer
Financing Receivable, Past Due [Line Items]
Current	669,008	658,392
Total Past Due	3,402	4,060
Total	672,410	662,452
Consumer | Direct installment
Financing Receivable, Past Due [Line Items]
Current	39,841	40,864
Total Past Due	205	185
Total	40,046	41,049
Consumer | Indirect installment
Financing Receivable, Past Due [Line Items]
Current	356,702	344,478
Total Past Due	2,423	2,946
Total	359,125	347,424
Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Current	272,465	273,050
Total Past Due	774	929
Total	273,239	273,979
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 11,039	$ 7,289
Total Past Due, Percentage of Total Loans	0.30%	0.20%
30-59 Days Past Due | Commercial
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 6,866	$ 1,819
30-59 Days Past Due | Commercial | Owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	4,532	920
30-59 Days Past Due | Commercial | Non-owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	2,021	80
30-59 Days Past Due | Commercial | Residential spec homes
Financing Receivable, Past Due [Line Items]
Total Past Due	135	0
30-59 Days Past Due | Commercial | Development & spec land
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
30-59 Days Past Due | Commercial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Past Due	178	819
30-59 Days Past Due | Real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	1,395	1,984
30-59 Days Past Due | Real estate | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total Past Due	1,395	1,984
30-59 Days Past Due | Real estate | Residential construction
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
30-59 Days Past Due | Real estate | Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
30-59 Days Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Total Past Due	2,778	3,486
30-59 Days Past Due | Consumer | Direct installment
Financing Receivable, Past Due [Line Items]
Total Past Due	190	175
30-59 Days Past Due | Consumer | Indirect installment
Financing Receivable, Past Due [Line Items]
Total Past Due	1,967	2,407
30-59 Days Past Due | Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Total Past Due	621	904
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 978	$ 440
Total Past Due, Percentage of Total Loans	0.03%	0.01%
60-89 Days Past Due | Commercial
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 589	$ 11
60-89 Days Past Due | Commercial | Owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	589	0
60-89 Days Past Due | Commercial | Non-owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Commercial | Residential spec homes
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Commercial | Development & spec land
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Commercial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Past Due	0	11
60-89 Days Past Due | Real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Real estate | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Real estate | Residential construction
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Real estate | Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Total Past Due	389	429
60-89 Days Past Due | Consumer | Direct installment
Financing Receivable, Past Due [Line Items]
Total Past Due	15	5
60-89 Days Past Due | Consumer | Indirect installment
Financing Receivable, Past Due [Line Items]
Total Past Due	260	404
60-89 Days Past Due | Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Total Past Due	114	20
90 Days or Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 246	$ 146
Total Past Due, Percentage of Total Loans	0.01%	0.01%
90 Days or Greater Past Due | Commercial
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 11	$ 0
90 Days or Greater Past Due | Commercial | Owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
90 Days or Greater Past Due | Commercial | Non-owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
90 Days or Greater Past Due | Commercial | Residential spec homes
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
90 Days or Greater Past Due | Commercial | Development & spec land
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
90 Days or Greater Past Due | Commercial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Past Due	11	0
90 Days or Greater Past Due | Real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	0	1
90 Days or Greater Past Due | Real estate | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total Past Due	0	1
90 Days or Greater Past Due | Real estate | Residential construction
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
90 Days or Greater Past Due | Real estate | Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
90 Days or Greater Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Total Past Due	235	145
90 Days or Greater Past Due | Consumer | Direct installment
Financing Receivable, Past Due [Line Items]
Total Past Due	0	5
90 Days or Greater Past Due | Consumer | Indirect installment
Financing Receivable, Past Due [Line Items]
Total Past Due	196	135
90 Days or Greater Past Due | Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 39	$ 5