Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest income
Interest and fees on loans	$ 666,950	$ 636,720	$ 565,537
Interest on federal funds sold and other short-term investments	21,338	19,268	16,035
Interest and dividends on securities:
Taxable	70,789	56,273	36,715
Tax-exempt	3,485	5,454	5,519
Total interest income	762,562	717,715	623,806
Interest expense
Interest on deposits	135,649	91,507	49,726
Interest on short-term borrowings	2,347	2,245	1,579
Interest on long-term borrowings	46,644	35,318	23,504
Total interest expense	184,640	129,070	74,809
Net interest income	577,922	588,645	548,997
Provision for loan losses	21,313	22,013	28,406
Net interest income after provision for loan losses	556,609	566,632	520,591
Other income
Income from bank-owned life insurance	7,339	5,045	5,110
Net gain on the sale of bank premises	0	2,763	0
Net investment securities gains (losses)	175	(2,618)	5,584
Other income	1,327	1,767	2,039
Total other income	150,484	128,712	131,645
Other expense
Employee compensation	173,962	164,468	166,393
Employee benefits	35,745	36,172	34,997
Net occupancy expense	34,850	36,462	39,067
Other real estate owned (OREO) expense	5,336	3,444	6,003
Equipment expense	14,210	13,846	10,528
Data processing expense	22,232	23,800	21,019
Bankcard processing expense	1,877	1,971	1,809
FDIC insurance expense	8,070	11,464	7,051
FHLB prepayment penalties	5,105	0	0
Other expense	81,267	76,552	80,542
Total other expense	382,654	368,179	367,409
Income before income taxes	324,439	327,165	284,827
Income taxes	64,340	70,823	134,246
Net income	$ 260,099	$ 256,342	$ 150,581
Earnings per common share:
Basic	$ 2.55	$ 2.46	$ 1.54
Diluted	2.55	2.45	1.54
Dividends per common share	$ 1.37	$ 1.36	$ 1.33
Average outstanding shares:
Basic	101,585,599	104,015,976	97,502,633
Diluted	101,852,577	104,298,825	97,890,078
Fees From Trust Services [Member]
Other income
Revenue from contract	$ 13,873	$ 12,930	$ 11,801
Fees from Brokerage Services [Member]
Other income
Revenue from contract	10,136	9,347	7,730
Fees from Deposit Services [Member]
Other income
Revenue from contract	33,768	33,973	33,622
Bankcard Fees and Merchant Discounts [Member]
Other income
Revenue from contract	4,674	5,168	4,795
Other Service Charges, Commissions, and Fees [Member]
Other income
Revenue from contract	2,241	2,228	2,057
Mortgage Banking [Member]
Other income
Revenue from contract	$ 76,951	$ 58,109	$ 58,907