Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income:
Loans, including fees	$ 669,002	$ 534,804	$ 458,094
Securities:
Taxable	86,370	92,979	103,025
Tax-exempt	233,358	222,620	210,918
Interest-bearing deposits	56,968	41,608	16,103
Federal funds sold and resell agreements	5,500	936	272
Total interest income	1,051,198	892,947	788,412
Interest expense:
Deposits	75,337	17,188	7,248
Federal funds purchased and repurchase agreements	8,021	1,522	204
Junior subordinated deferrable interest debentures	5,291	3,955	3,281
Other long-term borrowings	4,657	3,860	1,343
Total interest expense	93,306	26,525	12,076
Net interest income	957,892	866,422	776,336
Provision for loan losses	21,613	35,460	51,673
Net interest income after provision for loan losses	936,279	830,962	724,663
Trust and investment management fees	119,391	110,675	104,240
Service Charges on Deposit Accounts	85,186	84,182	81,203
Non-interest income:
Insurance commissions and fees	48,967	46,169	47,154
Interchange and debit card transaction fees	13,877	23,232	21,369
Other charges, commissions and fees	37,231	39,931	39,623
Net gain (loss) on securities transactions	(156)	(4,941)	14,975
Other	46,790	37,222	41,144
Total non-interest income	351,286	336,470	349,708
Non-interest expense:
Salaries and wages	350,312	337,068	318,665
Employee benefits	77,323	74,575	72,615
Net occupancy	76,788	75,971	71,627
Technology, furniture and equipment	83,102	74,335	71,208
Deposit insurance	16,397	20,128	17,428
Intangible amortization	1,424	1,703	2,429
Other	173,538	175,289	178,988
Total non-interest expense	778,884	759,069	732,960
Income before income taxes	508,681	408,363	341,411
Income taxes	53,763	44,214	37,150
Net income	454,918	364,149	304,261
Preferred stock dividends	8,063	8,063	8,063
Net income available to common shareholders	$ 446,855	$ 356,086	$ 296,198
Earnings per common share:
Basic (in dollars per share)	$ 6.97	$ 5.56	$ 4.73
Diluted (in dollars per share)	$ 6.90	$ 5.51	$ 4.70