Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loans including fees:
Taxable	$ 569,718	$ 508,293	$ 389,219
Nontaxable	15,919	16,299	13,970
Investment securities:
Taxable	113,832	80,168	63,031
Nontaxable	29,248	26,655	28,858
Money market and other interest-earning investments	1,670	630	258
Total interest income	730,387	632,045	495,336
Interest Expense
Deposits	69,364	41,277	20,356
Federal funds purchased and interbank borrowings	5,656	4,793	1,966
Securities sold under agreements to repurchase	2,517	1,962	1,270
Federal Home Loan Bank advances	37,452	34,925	24,818
Other borrowings	11,125	11,486	9,758
Total interest expense	126,114	94,443	58,168
Net interest income	604,273	537,602	437,168
Provision for loan losses	4,747	6,966	3,050
Net interest income after provision for loan losses	599,526	530,636	434,118
Noninterest Income
Wealth management fees	37,072	36,863	37,316
Service charges on deposit accounts	44,915	44,026	41,331
Debit card and ATM fees	21,652	20,216	17,676
Mortgage banking revenue	26,622	17,657	18,449
Investment product fees	21,785	20,539	20,977
Capital markets income	13,270	4,934	6,544
Company-owned life insurance	11,539	10,584	8,654
Net debt securities gains (losses)	1,923	2,060	9,135
Net gain on branch divestitures		13,989
Other income	20,539	24,437	23,300
Total noninterest income	199,317	195,305	183,382
Noninterest Expense
Salaries and employee benefits	289,452	281,275	246,738
Occupancy	55,255	51,941	46,511
Equipment	16,903	14,861	13,560
Marketing	15,898	15,847	13,172
Data processing	37,589	36,170	32,306
Communication	10,702	10,846	9,284
Professional fees	22,854	14,503	16,840
Loan expenses	7,253	7,028	6,596
FDIC assessment	6,030	10,638	9,480
Amortization of intangibles	16,911	14,442	11,841
Amortization of tax credit investments	2,749	22,949	11,733
Other expense	26,891	36,761	30,775
Total noninterest expense	508,487	517,261	448,836
Income before income taxes	290,356	208,680	168,664
Income tax expense	52,150	17,850	72,939
Net income	$ 238,206	$ 190,830	$ 95,725
Net income per common share - basic	$ 1.39	$ 1.23	$ 0.69
Net income per common share - diluted	$ 1.38	$ 1.22	$ 0.69
Weighted average number of common shares outstanding - basic	171,907	155,675	137,821
Weighted average number of common shares outstanding - diluted	172,687	156,539	138,513
Dividends per common share	$ 0.52	$ 0.52	$ 0.52