Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Interest income:
Loans, including fees	$ 135,388	$ 129,852	$ 267,222	$ 256,893
Investment securities:
Taxable	9,551	9,048	18,148	17,836
Tax-exempt	1,617	1,614	3,113	3,173
Federal funds sold and securities purchased under agreements to resell	3,426	1,218	4,889	1,878
Total interest income	149,982	141,732	293,372	279,780
Interest expense:
Deposits	17,393	10,009	34,038	16,922
Federal funds purchased and securities sold under agreements to repurchase	673	642	1,426	1,096
Other borrowings	4,737	1,519	7,462	3,227
Total interest expense	22,803	12,170	42,926	21,245
Net interest income	127,179	129,562	250,446	258,535
Provision for loan losses	3,704	4,478	5,192	6,932
Net interest income after provision for loan losses	123,475	125,084	245,254	251,603
Noninterest income:
Securities gains (losses), net	1,709	(641)	2,250	(641)
Recoveries on acquired loans	1,347	2,167	3,214	5,142
Other	2,794	2,503	4,982	5,078
Total noninterest income	37,618	37,525	69,676	78,080
Noninterest expense:
Salaries and employee benefits	58,547	55,026	116,978	117,491
Net occupancy expense	7,616	7,815	14,815	15,981
Information services expense	8,671	8,903	17,680	18,641
Furniture and equipment expense	4,233	4,519	8,646	9,145
OREO expense and loan related	881	1,037	1,632	2,698
Pension plan termination expense	9,526		9,526
Amortization of intangibles	3,268	3,722	6,549	7,135
Supplies, printing and postage expense	1,495	1,406	2,999	2,798
Professional fees	2,781	1,898	5,021	3,597
FDIC assessment and other regulatory charges	1,455	3,277	2,990	4,540
Advertising and marketing	959	1,163	1,766	1,899
Merger and branch consolidation related expense	2,078	14,096	3,058	25,392
Other	7,897	7,644	15,986	14,652
Total noninterest expense	109,407	110,506	207,646	223,969
Earnings:
Income before provision for income taxes	51,686	52,103	107,284	105,714
Provision for income taxes	10,226	11,644	21,457	22,929
Net income	$ 41,460	$ 40,459	$ 85,827	$ 82,785
Earnings per common share:
Basic (in dollars per share)	$ 1.18	$ 1.10	$ 2.43	$ 2.25
Diluted (in dollars per share)	$ 1.17	$ 1.09	$ 2.42	$ 2.24
Weighted average common shares outstanding:
Basic (in shares)	35,089	36,677	35,268	36,657
Diluted (in shares)	35,300	36,929	35,461	36,910
Fees on deposit accounts
Noninterest income:
Noninterest income	$ 18,741	$ 22,612	$ 36,549	$ 45,155
Mortgage banking income
Noninterest income:
Noninterest income	5,307	3,317	7,692	8,265
Trust and investment services income
Noninterest income:
Noninterest income	$ 7,720	$ 7,567	$ 14,989	$ 15,081