Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest income:
Loans, including fees	$ 151,202	$ 122,600
Securities:
Taxable	20,558	25,302
Tax-exempt	56,711	56,947
Interest-bearing deposits	14,094	6,836
Federal funds sold and resell agreements	761	107
Total interest income	243,326	211,792
Interest expense:
Deposits	10,638	1,868
Federal funds purchased and repurchase agreements	634	139
Junior subordinated deferrable interest debentures	1,142	908
Other long-term borrowings	1,164	368
Total interest expense	13,578	3,283
Net interest income	229,748	208,509
Provision for loan losses	6,945	7,952
Net interest income after provision for loan losses	222,803	200,557
Non-interest income:
Trust and investment management fees	29,587	26,470
Service charges on deposit accounts	20,843	20,769
Insurance commissions and fees	15,980	13,821
Interchange and debit card transaction fees	3,158	5,574
Other charges, commissions and fees	9,007	9,592
Net gain (loss) on securities transactions	(19)	0
Other	12,889	7,474
Total non-interest income	91,445	83,700
Non-interest expense:
Salaries and wages	86,683	82,512
Employee benefits	21,995	21,625
Net occupancy	19,740	19,237
Technology, furniture and equipment	19,679	17,990
Deposit insurance	4,879	4,915
Intangible amortization	388	458
Other	43,247	41,178
Total non-interest expense	196,611	187,915
Income before income taxes	117,637	96,342
Income taxes	11,157	11,401
Net income	106,480	84,941
Preferred stock dividends	2,016	2,016
Net income available to common shareholders	$ 104,464	$ 82,925
Earnings per common share:
Basic	$ 1.63	$ 1.29
Diluted	$ 1.61	$ 1.28