Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INTEREST INCOME
Loans	$ 687,771	$ 710,935	$ 616,037
Interest bearing balances due from banks and federal funds sold	4,383	7,486	5,996
Investment securities	64,533	63,376	53,460
Mortgage loans held for sale	3,031	1,326	1,336
TOTAL INTEREST INCOME	759,718	783,123	676,829
INTEREST EXPENSE
Deposits	79,860	139,011	87,210
Federal funds purchased and securities sold under agreements to repurchase	1,715	1,010	423
Other borrowings	19,652	23,008	23,654
Subordinated notes and debentures	18,757	18,341	16,848
TOTAL INTEREST EXPENSE	119,984	181,370	128,135
NET INTEREST INCOME	639,734	601,753	548,694
Provision for credit losses	74,973	43,240	38,148
NET INTEREST INCOME AFTER PROVISION FOR CREDIT LOSSES	564,761	558,513	510,546
NON-INTEREST INCOME
Investment banking income	2,681	2,313	3,141
Bank owned life insurance income	5,815	4,768	4,415
Gain on sale of securities, net	54,806	13,314	61
Other income	38,547	62,015	23,721
TOTAL NON-INTEREST INCOME	248,528	205,031	147,754
NON-INTEREST EXPENSE
Salaries and employee benefits	242,474	227,795	216,743
Occupancy expense, net	37,556	32,008	29,610
Furniture and equipment expense	24,038	18,220	16,323
Other real estate and foreclosure expense	1,752	3,442	4,480
Deposit insurance	9,184	4,416	8,721
Merger related costs	4,531	36,379	4,777
Other operating expenses	173,960	138,852	111,575
TOTAL NON-INTEREST EXPENSE	493,495	461,112	392,229
INCOME BEFORE INCOME TAXES	319,794	302,432	266,071
Provision for income taxes	64,890	64,265	50,358
NET INCOME	254,904	238,167	215,713
Preferred stock dividends	52	339	0
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 254,852	$ 237,828	$ 215,713
Basic earnings per share (in dollars per share)	$ 2.32	$ 2.42	$ 2.34
Diluted earnings per share (in dollars per share)	$ 2.31	$ 2.41	$ 2.32
Trust income
NON-INTEREST INCOME
NON-INTEREST INCOME	$ 27,705	$ 25,040	$ 23,128
Service charges on deposit accounts
NON-INTEREST INCOME
NON-INTEREST INCOME	43,082	44,782	42,508
Other service charges and fees
NON-INTEREST INCOME
NON-INTEREST INCOME	6,624	5,824	7,469
Mortgage lending income
NON-INTEREST INCOME
NON-INTEREST INCOME	34,469	15,017	9,230
SBA lending income
NON-INTEREST INCOME
NON-INTEREST INCOME	1,329	2,669	1,813
Debit and credit card fees
NON-INTEREST INCOME
NON-INTEREST INCOME	$ 33,470	$ 29,289	$ 32,268