CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest income:
Loans, including fees	$ 224,482	$ 247,147	$ 687,183	$ 714,179
Securities:
Taxable	8,276	10,655	28,133	36,438
Tax-exempt	15,001	13,313	43,421	37,541
Federal funds sold and other	1,429	4,634	5,258	11,325
Total interest income	249,188	275,749	763,995	799,483
Interest expense:
Deposits	28,401	62,531	112,826	175,736
Securities sold under agreements to repurchase	77	152	286	439
Federal Home Loan Bank advances and other borrowings	14,116	17,260	50,080	51,338
Total interest expense	42,594	79,943	163,192	227,513
Net interest income	206,594	195,806	600,803	571,970
Provision for credit losses	16,333	8,260	184,554	22,639
Net interest income after provision for credit losses	190,261	187,546	416,249	549,331
Noninterest income:
Total noninterest income	91,065	82,619	234,396	204,364
Noninterest expense:
Salaries and employee benefits	90,103	85,919	244,470	231,915
Equipment and occupancy	21,622	20,348	64,626	63,523
Other real estate expense, net	1,795	655	7,098	3,424
Marketing and other business development	2,321	2,723	7,714	8,953
Postage and supplies	1,761	1,766	5,821	5,737
Amortization of intangibles	2,417	2,430	7,416	7,012
Other noninterest expense	24,258	19,100	76,086	54,114
Total noninterest expense	144,277	132,941	413,231	374,678
Income before income taxes	137,049	137,224	237,414	379,017
Income tax expense	26,404	26,703	35,969	74,215
Net income	110,645	110,521	201,445	304,802
Preferred stock dividends	(3,798)	0	(3,798)	0
Net income available to common shareholders	$ 106,847	$ 110,521	$ 197,647	$ 304,802
Per share information:
Basic net income per common share (in dollars per share)	$ 1.42	$ 1.45	$ 2.62	$ 3.99
Diluted net income per common share (in dollars per share)	$ 1.42	$ 1.44	$ 2.62	$ 3.97
Weighted average common shares outstanding:
Basic (in shares)	75,240,664	76,301,010	75,417,663	76,480,757
Diluted (in shares)	75,360,033	76,556,309	75,544,677	76,761,167
Service charges on deposit accounts
Noninterest income:
Total noninterest income	$ 9,854	$ 10,193	$ 25,796	$ 27,675
Investment services
Noninterest income:
Total noninterest income	6,734	6,270	21,944	17,607
Insurance sales commissions
Noninterest income:
Total noninterest income	2,284	2,252	7,755	7,327
Gain on mortgage loans sold, net
Noninterest income:
Total noninterest income	19,453	7,402	47,655	18,291
Investment gains (losses) on sales, net
Noninterest income:
Total noninterest income	651	417	986	(6,009)
Trust fees
Noninterest income:
Total noninterest income	3,986	3,593	12,114	10,349
Income from equity method investment
Noninterest income:
Total noninterest income	26,445	32,248	59,245	77,799
Other noninterest income
Noninterest income:
Total noninterest income	$ 21,658	$ 20,244	$ 58,901	$ 51,325