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 and leases	$ 789,719	$ 924,693	$ 842,449
Taxable interest and dividends on securities	189,683	207,294	191,493
Non-taxable interest on securities	21,878	21,869	20,597
Loans held for sale	769	727	628
Interest income	1,002,049	1,154,583	1,055,167
Interest Expense:
Deposits	67,897	129,577	90,407
Securities sold under agreements to repurchase and other borrowings	5,941	17,953	13,491
Federal Home Loan Bank advances	18,767	31,399	33,461
Long-term debt	18,051	20,527	11,127
Interest expense	110,656	199,456	148,486
Net interest income	891,393	955,127	906,681
Provision for credit losses	137,750	37,800	42,000
Net interest income (loss) after provision for loan and lease losses	753,643	917,327	864,681
Non-interest Income:
Deposit service fees	156,032	168,022	162,183
Loan and lease related fees	29,127	31,327	32,025
Wealth and investment services	32,916	32,932	32,843
Mortgage banking activities	18,295	6,115	4,424
Increase in cash surrender value of life insurance policies	14,561	14,612	14,614
Gain on the sale of investment securities, net	8	29	0
Other income	34,338	32,278	36,479
Total non-interest income	285,277	285,315	282,568
Non-interest Expense:
Compensation and benefits	428,391	395,402	381,496
Occupancy	71,029	57,181	59,463
Technology and equipment	112,273	105,283	97,877
Intangible assets amortization	4,160	3,847	3,847
Marketing	14,125	16,286	16,838
Professional and outside services	32,424	21,380	20,300
Deposit insurance	18,316	17,954	34,749
Other expense	78,228	98,617	91,046
Total non-interest expense	758,946	715,950	705,616
Income before income tax expense	279,974	486,692	441,633
Income tax expense	59,353	103,969	81,215
Net income	220,621	382,723	360,418
Preferred stock dividends and other	(9,147)	(9,738)	(8,715)
Earnings applicable to common shareholders	$ 211,474	$ 372,985	$ 351,703
Earnings per common share:
Earnings per common share, Basic (in dollars per share)	$ 2.35	$ 4.07	$ 3.83
Earnings per common share, Diluted (in dollars per share)	$ 2.35	$ 4.06	$ 3.81