Loans - Aging analysis of past due loans (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Loans and Allowance for Loan Losses
Non-Accruing	$ 88,383	$ 95,188
Total loans	23,788,949	24,664,134
30 days past due
Loans and Allowance for Loan Losses
Total loans	63,121	20,185
60 days past due
Loans and Allowance for Loan Losses
Total loans	15,855	29,380
90 days past due
Loans and Allowance for Loan Losses
Total loans	1,818	11,651
Total Past Due
Loans and Allowance for Loan Losses
Total loans	80,794	61,216
Current
Loans and Allowance for Loan Losses
Total loans	23,619,772	24,507,730
Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	14,978,428	12,289,456
Construction and land development
Loans and Allowance for Loan Losses
Non-Accruing	1,857	2,421
Total loans	2,032,731	1,890,846
Construction and land development | 30 days past due
Loans and Allowance for Loan Losses
Total loans	1,696	520
Construction and land development | 60 days past due
Loans and Allowance for Loan Losses
Total loans	426	1,142
Construction and land development | Total Past Due
Loans and Allowance for Loan Losses
Total loans	2,122	1,662
Construction and land development | Current
Loans and Allowance for Loan Losses
Total loans	2,028,752	1,886,763
Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Non-Accruing	24,326	28,477
Total loans	3,569,791	3,682,667
Consumer Owner Occupied Loans | 30 days past due
Loans and Allowance for Loan Losses
Total loans	2,097	1,165
Consumer Owner Occupied Loans | 60 days past due
Loans and Allowance for Loan Losses
Total loans	610	3,294
Consumer Owner Occupied Loans | 90 days past due
Loans and Allowance for Loan Losses
Total loans		34
Consumer Owner Occupied Loans | Total Past Due
Loans and Allowance for Loan Losses
Total loans	2,707	4,493
Consumer Owner Occupied Loans | Current
Loans and Allowance for Loan Losses
Total loans	3,542,758	3,649,697
Home equity loans
Loans and Allowance for Loan Losses
Non-Accruing	8,592	9,926
Total loans	1,163,776	1,292,141
Home equity loans | 30 days past due
Loans and Allowance for Loan Losses
Total loans	1,509	1,805
Home equity loans | 60 days past due
Loans and Allowance for Loan Losses
Total loans	837	481
Home equity loans | Total Past Due
Loans and Allowance for Loan Losses
Total loans	2,346	2,286
Home equity loans | Current
Loans and Allowance for Loan Losses
Total loans	1,152,838	1,279,929
Commercial and industrial
Loans and Allowance for Loan Losses
Non-Accruing	5,688	9,218
Total loans	3,959,726	5,046,310
Commercial and industrial | 30 days past due
Loans and Allowance for Loan Losses
Total loans	38,439	10,979
Commercial and industrial | 60 days past due
Loans and Allowance for Loan Losses
Total loans	10,234	22,089
Commercial and industrial | 90 days past due
Loans and Allowance for Loan Losses
Total loans	876	10,864
Commercial and industrial | Total Past Due
Loans and Allowance for Loan Losses
Total loans	49,549	43,932
Commercial and industrial | Current
Loans and Allowance for Loan Losses
Total loans	3,904,489	4,993,160
Other income producing property
Loans and Allowance for Loan Losses
Non-Accruing	3,945	7,543
Total loans	762,408	854,900
Other income producing property | 30 days past due
Loans and Allowance for Loan Losses
Total loans	2,333	897
Other income producing property | 60 days past due
Loans and Allowance for Loan Losses
Total loans	386	338
Other income producing property | 90 days past due
Loans and Allowance for Loan Losses
Total loans	48	278
Other income producing property | Total Past Due
Loans and Allowance for Loan Losses
Total loans	2,767	1,513
Other income producing property | Current
Loans and Allowance for Loan Losses
Total loans	755,696	845,844
Consumer loans
Loans and Allowance for Loan Losses
Non-Accruing	4,270	6,074
Total loans	912,445	894,334
Consumer loans | 30 days past due
Loans and Allowance for Loan Losses
Total loans	1,368	1,718
Consumer loans | 60 days past due
Loans and Allowance for Loan Losses
Total loans	785	818
Consumer loans | 90 days past due
Loans and Allowance for Loan Losses
Total loans		4
Consumer loans | Total Past Due
Loans and Allowance for Loan Losses
Total loans	2,153	2,540
Consumer loans | Current
Loans and Allowance for Loan Losses
Total loans	906,022	885,720
Other loans
Loans and Allowance for Loan Losses
Total loans	30,798	17,993
Other loans | 30 days past due
Loans and Allowance for Loan Losses
Total loans		13
Other loans | 60 days past due
Loans and Allowance for Loan Losses
Total loans		6
Other loans | Total Past Due
Loans and Allowance for Loan Losses
Total loans		19
Other loans | Current
Loans and Allowance for Loan Losses
Total loans	30,798	17,974
Commercial loans
Loans and Allowance for Loan Losses
Total loans	17,428,544	18,076,076
Commercial loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	1,367,743	1,231,510
Commercial loans | Commercial non-owner occupied
Loans and Allowance for Loan Losses
Non-Accruing	20,098	5,470
Total loans	6,368,784	6,152,246
Commercial loans | Commercial non-owner occupied | 30 days past due
Loans and Allowance for Loan Losses
Total loans	4,418	188
Commercial loans | Commercial non-owner occupied | 60 days past due
Loans and Allowance for Loan Losses
Total loans	1,197	372
Commercial loans | Commercial non-owner occupied | 90 days past due
Loans and Allowance for Loan Losses
Total loans		471
Commercial loans | Commercial non-owner occupied | Total Past Due
Loans and Allowance for Loan Losses
Total loans	5,615	1,031
Commercial loans | Commercial non-owner occupied | Current
Loans and Allowance for Loan Losses
Total loans	6,343,071	6,145,745
Commercial loans | Commercial owner occupied real estate loan
Loans and Allowance for Loan Losses
Non-Accruing	19,607	26,059
Total loans	4,988,490	4,832,697
Commercial loans | Commercial owner occupied real estate loan | 30 days past due
Loans and Allowance for Loan Losses
Total loans	11,261	2,900
Commercial loans | Commercial owner occupied real estate loan | 60 days past due
Loans and Allowance for Loan Losses
Total loans	1,380	840
Commercial loans | Commercial owner occupied real estate loan | 90 days past due
Loans and Allowance for Loan Losses
Total loans	894
Commercial loans | Commercial owner occupied real estate loan | Total Past Due
Loans and Allowance for Loan Losses
Total loans	13,535	3,740
Commercial loans | Commercial owner occupied real estate loan | Current
Loans and Allowance for Loan Losses
Total loans	4,955,348	4,802,898
Commercial loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	34,543	35,137
Commercial loans | Commercial and industrial
Loans and Allowance for Loan Losses
Total loans	3,959,726	5,046,310
Commercial loans | Other income producing property
Loans and Allowance for Loan Losses
Total loans	678,460	760,183
Commercial loans | Other loans
Loans and Allowance for Loan Losses
Total loans	30,798	17,993
Consumer portfolio loans
Loans and Allowance for Loan Losses
Total loans	6,360,405	6,588,058
Consumer portfolio loans | 30 days past due
Loans and Allowance for Loan Losses
Total loans	8,206	47,904
Consumer portfolio loans | 60 days past due
Loans and Allowance for Loan Losses
Total loans	4,482	7,281
Consumer portfolio loans | 90 days past due
Loans and Allowance for Loan Losses
Total loans	13,805	14,549
Consumer portfolio loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	664,988	659,336
Consumer portfolio loans | Construction and land development | 30 days past due
Loans and Allowance for Loan Losses
Total loans	207	12,432
Consumer portfolio loans | Construction and land development | 60 days past due
Loans and Allowance for Loan Losses
Total loans		720
Consumer portfolio loans | Construction and land development | 90 days past due
Loans and Allowance for Loan Losses
Total loans	205	52
Consumer portfolio loans | Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Total loans	3,535,248	3,647,530
Consumer portfolio loans | Consumer Owner Occupied Loans | 30 days past due
Loans and Allowance for Loan Losses
Total loans	4,238	30,020
Consumer portfolio loans | Consumer Owner Occupied Loans | 60 days past due
Loans and Allowance for Loan Losses
Total loans	2,146	4,871
Consumer portfolio loans | Consumer Owner Occupied Loans | 90 days past due
Loans and Allowance for Loan Losses
Total loans	8,564	7,563
Consumer portfolio loans | Home equity loans
Loans and Allowance for Loan Losses
Total loans	1,163,776	1,292,141
Consumer portfolio loans | Home equity loans | 30 days past due
Loans and Allowance for Loan Losses
Total loans	2,184	2,861
Consumer portfolio loans | Home equity loans | 60 days past due
Loans and Allowance for Loan Losses
Total loans	998	534
Consumer portfolio loans | Home equity loans | 90 days past due
Loans and Allowance for Loan Losses
Total loans	2,587	4,123
Consumer portfolio loans | Other income producing property
Loans and Allowance for Loan Losses
Total loans	83,948	94,717
Consumer portfolio loans | Other income producing property | 30 days past due
Loans and Allowance for Loan Losses
Total loans	17	240
Consumer portfolio loans | Other income producing property | 60 days past due
Loans and Allowance for Loan Losses
Total loans	109	331
Consumer portfolio loans | Other income producing property | 90 days past due
Loans and Allowance for Loan Losses
Total loans	919	223
Consumer portfolio loans | Consumer loans
Loans and Allowance for Loan Losses
Total loans	912,445	894,334
Consumer portfolio loans | Consumer loans | 30 days past due
Loans and Allowance for Loan Losses
Total loans	1,560	2,351
Consumer portfolio loans | Consumer loans | 60 days past due
Loans and Allowance for Loan Losses
Total loans	1,229	825
Consumer portfolio loans | Consumer loans | 90 days past due
Loans and Allowance for Loan Losses
Total loans	$ 1,530	$ 2,588