Allowance for Credit Losses - Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 92,733	$ 35,154
Initial Allowance on PCD Loans Acquired During the Period		516
Provision for credit losses	(5,715)	29,513
Charge- Offs	(941)	(1,647)
Recoveries	571	673
TDR Allowance Adjustments	(5)	(24)
Ending Balance	86,643	85,411
Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	4,920	1,842
Initial Allowance on PCD Loans Acquired During the Period		48
Provision for credit losses	(510)	1,248
Charge- Offs	0	0
Recoveries	18	29
TDR Allowance Adjustments	0	0
Ending Balance	4,428	4,646
Commercial real estate - owner-occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	9,868	5,361
Initial Allowance on PCD Loans Acquired During the Period		207
Provision for credit losses	(76)	(264)
Charge- Offs	0	(44)
Recoveries	0	0
TDR Allowance Adjustments	0	(13)
Ending Balance	9,792	5,327
Commercial real estate - non owner-occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	38,266	7,863
Initial Allowance on PCD Loans Acquired During the Period		140
Provision for credit losses	(2,038)	18,283
Charge- Offs	0	(12)
Recoveries	1	28
TDR Allowance Adjustments	0	0
Ending Balance	36,229	35,643
Residential real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	17,500	7,667
Initial Allowance on PCD Loans Acquired During the Period		97
Provision for credit losses	(3,372)	6,260
Charge- Offs	0	(18)
Recoveries	229	116
TDR Allowance Adjustments	(4)	(10)
Ending Balance	14,353	19,899
Commercial and financial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	18,690	9,716
Initial Allowance on PCD Loans Acquired During the Period		11
Provision for credit losses	775	2,746
Charge- Offs	(756)	(1,100)
Recoveries	207	420
TDR Allowance Adjustments	0	0
Ending Balance	18,916	15,470
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	3,489	2,705
Initial Allowance on PCD Loans Acquired During the Period		13
Provision for credit losses	(494)	1,240
Charge- Offs	(185)	(473)
Recoveries	116	80
TDR Allowance Adjustments	(1)	(1)
Ending Balance	2,925	4,426
Paycheck Protection Program
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	0
Provision for credit losses	0
Charge- Offs	0
Recoveries	0
TDR Allowance Adjustments	0
Ending Balance	$ 0
Cumulative change in accounting principle upon adoption of new accounting pronouncement
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance		21,226
Cumulative change in accounting principle upon adoption of new accounting pronouncement | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance		1,479
Cumulative change in accounting principle upon adoption of new accounting pronouncement | Commercial real estate - owner-occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance		80
Cumulative change in accounting principle upon adoption of new accounting pronouncement | Commercial real estate - non owner-occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance		9,341
Cumulative change in accounting principle upon adoption of new accounting pronouncement | Residential real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance		5,787
Cumulative change in accounting principle upon adoption of new accounting pronouncement | Commercial and financial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance		3,677
Cumulative change in accounting principle upon adoption of new accounting pronouncement | Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance		$ 862