Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Interest income:
Loans, including fees	$ 112,586	$ 105,666
Securities:
Taxable	25,974	30,172
Tax-exempt	50,333	46,546
Interest-bearing deposits	3,653	1,970
Federal funds sold and resell agreements	58	20
Total interest income	192,604	184,374
Interest expense:
Deposits	1,787	2,756
Federal funds purchased and repurchase agreements	56	36
Junior subordinated deferrable interest debentures	750	655
Other long-term borrowings	287	224
Total interest expense	2,880	3,671
Net interest income	189,724	180,703
Provision for loan losses	28,500	8,162
Net interest income after provision for loan losses	161,224	172,541
Non-interest income:
Trust and investment management fees	25,334	27,161
Service charges on deposit accounts	20,364	19,777
Insurance commissions and fees	15,423	14,635
Interchange and debit card transaction fees	5,022	4,643
Other charges, commissions and fees	9,053	8,441
Net gain (loss) on securities transactions	14,903	228
Other	6,044	8,330
Total non-interest income	96,143	83,215
Non-interest expense:
Salaries and wages	79,297	76,072
Employee benefits	20,305	20,227
Net occupancy	17,187	15,081
Furniture and equipment	17,517	15,534
Deposit insurance	3,657	3,613
Intangible amortization	664	894
Other	40,532	40,090
Total non-interest expense	179,159	171,511
Income before income taxes	78,208	84,245
Income taxes	9,429	12,082
Net income	68,779	72,163
Preferred stock dividends	2,016	2,016
Net income available to common shareholders	$ 66,763	$ 70,147
Earnings per common share:
Basic	$ 1.07	$ 1.11
Diluted	$ 1.07	$ 1.10