Condensed Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Interest and Dividend Income, Operating [Abstract]
Interest and fees on loans and leases	$ 216,187	$ 228,764
Taxable interest and dividends on investments	52,622	51,876
Non-taxable interest on investment securities	5,486	5,402
Loans held for sale	175	148
Total interest income	274,470	286,190
Interest Expense [Abstract]
Deposits	27,843	31,020
Securities sold under agreements to repurchase and other borrowings	3,730	2,752
Federal Home Loan Bank advances	6,869	7,785
Long-term debt	5,227	3,082
Total interest expense	43,669	44,639
Net interest income	230,801	241,551
Provision for credit losses	76,085	8,600
Net interest income after provision for credit losses	154,801	232,951
Noninterest Income [Abstract]
Deposit service fees	42,570	43,024
Loan and lease related fees	6,496	7,819
Wealth and investment services	8,739	7,651
Mortgage banking activities	2,893	764
Increase in cash surrender value of life insurance policies	3,580	3,584
Gain on Sale of Investments	8	0
Other income	9,092	5,770
Total non-interest income	73,378	68,612
Noninterest Expense [Abstract]
Compensation and benefits	101,887	97,785
Occupancy	14,485	14,696
Technology and equipment	27,837	25,697
Intangible assets amortization	962	962
Marketing	3,502	3,328
Professional and outside services	5,663	6,048
Deposit insurance	4,725	4,430
Other expense	19,775	22,740
Total non-interest expense	178,836	175,686
Income before income tax expense	49,343	125,877
Income tax expense	11,144	26,141
Net income	38,199	99,736
Preferred stock dividends and other	(2,178)	(2,187)
Net Income (Loss) Available to Common Stockholders, Basic, Total	$ 36,021	$ 97,549
Earnings Per Share, Basic and Diluted [Abstract]
Basic	$ 0.40	$ 1.06
Diluted	$ 0.39	$ 1.06
Provision for credit losses	$ 76,000	$ 8,600