CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest Income
Interest and fees on loans	$ 1,284,707	$ 1,198,908	$ 1,033,993
Interest and dividends on investment securities:
Taxable	70,249	86,926	87,306
Tax-exempt	14,563	17,420	21,504
Dividends	11,644	12,023	13,209
Interest on federal funds sold and other short-term investments	2,556	5,723	3,236
Total interest income	1,383,719	1,321,000	1,159,248
Interest on deposits:
Savings, NOW and money market	76,169	145,177	108,394
Time	106,067	166,693	81,959
Interest on short-term borrowings	11,372	47,862	45,930
Interest on long-term borrowings and junior subordinated debentures	71,207	63,220	65,762
Total interest expense	264,815	422,952	302,045
Net Interest Income	1,118,904	898,048	857,203
Provision for credit losses for held to maturity securities	635	0	0
Provision for credit losses for loans	125,087	24,218	32,501
Net Interest Income After Provision for Credit Losses	993,182	873,830	824,702
Non-Interest Income
Insurance commissions	7,398	10,409	15,213
Gains (losses) on securities transactions, net	524	(150)	(2,342)
Other-than-temporary impairment losses on securities	0	(2,928)	0
Fees from loan servicing	10,352	9,794	9,319
Gains on sales of loans, net	42,251	18,914	20,515
(Losses) gains on sales of assets, net	(1,891)	78,333	(2,401)
Bank owned life insurance	10,083	8,232	8,691
Other	83,643	55,634	45,607
Non-interest income	183,032	214,520	134,052
Non-Interest Expense
Salary and employee benefits expense	333,221	327,431	333,816
Net occupancy and equipment expense	129,002	118,191	108,763
FDIC insurance assessment	18,949	21,710	28,266
Amortization of other intangible assets	24,645	18,080	18,416
Professional and legal fees	32,348	20,810	34,141
Loss on extinguishment of debt	12,036	31,995	0
Amortization of tax credit investments	13,335	20,392	24,200
Telecommunication expenses	10,737	9,883	12,102
Other	71,875	63,063	69,357
Total non-interest expense	646,148	631,555	629,061
Income Before Income Taxes	530,066	456,795	329,693
Income tax expense	139,460	147,002	68,265
Net Income	390,606	309,793	261,428
Dividends on preferred stock	12,688	12,688	12,688
Net Income Available to Common Shareholders	$ 377,918	$ 297,105	$ 248,740
Earnings Per Common Share:
Basic (in USD per share)	$ 0.94	$ 0.88	$ 0.75
Diluted (in USD per share)	0.93	0.87	0.75
Cash dividends declared per common share (in USD per share)	$ 0.44	$ 0.44	$ 0.44
Weighted Average Number of Common Shares Outstanding:
Basic (in shares)	403,754,356	337,792,270	331,258,964
Diluted (in shares)	405,046,207	340,117,808	332,693,718
Trust and Investment Services
Non-Interest Income
Services	$ 12,415	$ 12,646	$ 12,633
Deposit Account
Non-Interest Income
Services	$ 18,257	$ 23,636	$ 26,817