Non-performing Loans - Payment Status by Class of Loan (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Current	$ 3,997,363	$ 3,609,036
Total Past Due	5,844	7,875
Total	$ 4,003,207	$ 3,616,911
Percentage of total loans	99.85%	99.78%
Total Past Due, percentage of total loans	0.15%	0.22%
Percent past due	100.00%	100.00%
Commercial
Financing Receivable, Past Due [Line Items]
Current	$ 2,304,494	$ 2,039,953
Total Past Due	1,114	1,830
Total	2,305,608	2,041,783
Commercial | Owner occupied real estate
Financing Receivable, Past Due [Line Items]
Current	491,393	515,604
Total Past Due	0	920
Total	491,393	516,524
Commercial | Non–owner occupied real estate
Financing Receivable, Past Due [Line Items]
Current	1,017,130	972,195
Total Past Due	520	80
Total	1,017,650	972,275
Commercial | Residential spec homes
Financing Receivable, Past Due [Line Items]
Current	11,190	12,925
Total Past Due	0	0
Total	11,190	12,925
Commercial | Development & spec land
Financing Receivable, Past Due [Line Items]
Current	25,771	35,881
Total Past Due	544	0
Total	26,315	35,881
Commercial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Current	759,010	503,348
Total Past Due	50	830
Total	759,060	504,178
Real estate
Financing Receivable, Past Due [Line Items]
Current	1,040,075	910,691
Total Past Due	2,204	1,985
Total	1,042,279	912,676
Real estate | Residential mortgage
Financing Receivable, Past Due [Line Items]
Current	641,882	740,712
Total Past Due	2,204	1,985
Total	644,086	742,697
Real estate | Residential construction
Financing Receivable, Past Due [Line Items]
Current	23,540	19,686
Total Past Due	0	0
Total	23,540	19,686
Real estate | Mortgage warehouse
Financing Receivable, Past Due [Line Items]
Current	374,653	150,293
Total Past Due	0	0
Total	374,653	150,293
Consumer
Financing Receivable, Past Due [Line Items]
Current	652,794	658,392
Total Past Due	2,526	4,060
Total	655,320	662,452
Consumer | Direct installment
Financing Receivable, Past Due [Line Items]
Current	38,974	40,864
Total Past Due	52	185
Total	39,026	41,049
Consumer | Indirect installment
Financing Receivable, Past Due [Line Items]
Current	357,060	344,478
Total Past Due	1,117	2,946
Total	358,177	347,424
Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Current	256,760	273,050
Total Past Due	1,357	929
Total	258,117	273,979
30–59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 4,691	$ 7,289
Total Past Due, percentage of total loans	0.12%	0.20%
30–59 Days Past Due | Commercial
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 826	$ 1,819
30–59 Days Past Due | Commercial | Owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	0	920
30–59 Days Past Due | Commercial | Non–owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	282	80
30–59 Days Past Due | Commercial | Residential spec homes
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
30–59 Days Past Due | Commercial | Development & spec land
Financing Receivable, Past Due [Line Items]
Total Past Due	544	0
30–59 Days Past Due | Commercial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Past Due	0	819
30–59 Days Past Due | Real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	1,894	1,984
30–59 Days Past Due | Real estate | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total Past Due	1,894	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	1,971	3,486
30–59 Days Past Due | Consumer | Direct installment
Financing Receivable, Past Due [Line Items]
Total Past Due	24	175
30–59 Days Past Due | Consumer | Indirect installment
Financing Receivable, Past Due [Line Items]
Total Past Due	878	2,407
30–59 Days Past Due | Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Total Past Due	1,069	904
60–89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 822	$ 440
Total Past Due, percentage of total loans	0.02%	0.01%
60–89 Days Past Due | Commercial
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 288	$ 11
60–89 Days Past Due | Commercial | Owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
60–89 Days Past Due | Commercial | Non–owner occupied real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	238	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	50	11
60–89 Days Past Due | Real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	105	0
60–89 Days Past Due | Real estate | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total Past Due	105	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	429	429
60–89 Days Past Due | Consumer | Direct installment
Financing Receivable, Past Due [Line Items]
Total Past Due	28	5
60–89 Days Past Due | Consumer | Indirect installment
Financing Receivable, Past Due [Line Items]
Total Past Due	170	404
60–89 Days Past Due | Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Total Past Due	231	20
90 Days or Greater Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 331	$ 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	$ 0	$ 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	0	0
90 Days or Greater Past Due | Real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	205	1
90 Days or Greater Past Due | Real estate | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total Past Due	205	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	126	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	69	135
90 Days or Greater Past Due | Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 57	$ 5