Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Loan Portfolio Held for Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Loan Portfolio [Abstract]
Total LHFI	$ 11,586,064		$ 10,247,829
Less ACL, LHFI	115,050	$ 103,140	99,457	$ 104,073	$ 104,032	$ 117,306
Net LHFI	11,471,014		10,148,372
Construction, Land Development and Other Land [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	693,741		596,968
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	566,985		517,683
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	2,030,127		1,460,310
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	593,119		726,043
Other Construction [Member] | Other Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	953,654		711,813
Secured by Nonfarm, Nonresidential Properties [Member] | Loans Secured by Real Estate [Member]
Loan Portfolio [Abstract]
Total LHFI	3,206,946		2,977,084
Commercial and Industrial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	1,689,532		1,414,279
Consumer Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	166,027		162,555
State and Other Political Subdivision Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	1,188,703		1,146,251
Other Commercial Loans [Member]
Loan Portfolio [Abstract]
Total LHFI	$ 497,230		$ 534,843