LHFI and ACL, LHFI - Loan Portfolio Held for Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Loan Portfolio [Abstract]
Total LHFI	$ 12,810,259		$ 12,204,039
Less ACL, LHFI	134,031	$ 129,298	120,214	$ 115,050	$ 103,140	$ 99,457
Net LHFI	12,676,228		12,083,825
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	655,381		690,616
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	603,818		590,790
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	2,289,788		2,185,057
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	1,218,499		742,538
Other Construction [Member] | Other Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	953,945		1,028,926
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	3,569,671		3,278,830
Less ACL, LHFI	23,298	20,376	19,488	25,924	29,735	37,912
Commercial and Industrial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	1,828,924		1,821,259
Less ACL, LHFI	23,755	23,170	23,140	24,104	14,103	18,939
Consumer Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	165,556		170,230
Less ACL, LHFI	5,804	5,540	5,792	5,028	5,139	4,774
State and Other Political Subdivision Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	1,056,569		1,223,863
Less ACL, LHFI	665	676	885	1,594	1,917	2,708
Other Commercial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	468,108		471,930
Less ACL, LHFI	$ 10,690	$ 5,607	$ 4,647	$ 4,698	$ 4,963	$ 5,348