LHFI and ACL, LHFI - Loan Portfolio Held for Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Loan Portfolio [Abstract]
Total LHFI	$ 12,497,195	$ 12,204,039
Less ACL, LHFI	122,239	120,214	$ 98,734	$ 99,457
Net LHFI	12,374,956	12,083,825
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	682,214	690,616
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	595,520	590,790
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	2,226,528	2,185,057
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	847,527	742,538
Other Construction [Member] | Other Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	1,041,558	1,028,926
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	3,375,579	3,278,830
Less ACL, LHFI	18,640	19,488	32,030	37,912
Commercial and Industrial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	1,914,137	1,821,259
Less ACL, LHFI	23,462	23,140	14,951	18,939
Consumer Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	166,464	170,230
Less ACL, LHFI	5,532	5,792	4,872	4,774
State and Other Political Subdivision Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	1,193,727	1,223,863
Less ACL, LHFI	729	885	2,371	2,708
Other Commercial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	453,941	471,930
Less ACL, LHFI	$ 5,710	$ 4,647	$ 4,077	$ 5,348