CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Interest income:
Loans, including fees	$ 229,379,000	$ 191,214,000
Securities:
Taxable	13,540,000	11,222,000
Tax-exempt	11,672,000	7,285,000
Federal funds sold and other	3,292,000	1,807,000
Total interest income	257,883,000	211,528,000
Interest expense:
Deposits	54,217,000	23,981,000
Securities sold under agreements to repurchase	145,000	130,000
Federal Home Loan Bank advances and other borrowings	16,275,000	12,946,000
Total interest expense	70,637,000	37,057,000
Net interest income	187,246,000	174,471,000
Provision for loan losses	7,184,000	6,931,000
Net interest income after provision for loan losses	180,062,000	167,540,000
Noninterest income:
Total noninterest income	51,063,000	44,183,000
Noninterest expense:
Salaries and employee benefits	70,376,000	63,719,000
Equipment and occupancy	19,331,000	17,743,000
Other real estate expense (income), net	246,000	(794,000)
Marketing and other business development	2,948,000	2,247,000
Postage and supplies	1,892,000	2,039,000
Amortization of intangibles	2,311,000	2,698,000
Merger-related expense	0	5,353,000
Other noninterest expense	16,947,000	15,575,000
Total noninterest expense	114,051,000	108,580,000
Income before income taxes	117,074,000	103,143,000
Income tax expense	23,114,000	19,633,000
Net income	$ 93,960,000	$ 83,510,000
Per share information:
Basic net income per common share (in dollars per share)	$ 1.22	$ 1.08
Diluted net income per common share (in dollars per share)	$ 1.22	$ 1.08
Weighted average shares outstanding:
Basic (in shares)	76,803,171	77,077,957
Diluted (in shares)	77,127,692	77,365,664
Service charges on deposit accounts
Noninterest income:
Total noninterest income	$ 8,542,000	$ 7,905,000
Investment services
Noninterest income:
Total noninterest income	5,404,000	5,245,000
Insurance sales commissions
Noninterest income:
Total noninterest income	2,928,000	3,119,000
Gain on mortgage loans sold, net
Noninterest income:
Total noninterest income	4,878,000	3,744,000
Gain on sale of investment securities, net
Noninterest income:
Total noninterest income	(1,960,000)	30,000
Trust fees
Noninterest income:
Total noninterest income	3,295,000	3,117,000
Income from equity method investment
Noninterest income:
Total noninterest income	13,290,000	9,360,000
Other noninterest income
Noninterest income:
Total noninterest income	$ 14,686,000	$ 11,663,000