Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest income:
Loans, including fees	$ 87,833	$ 75,401
Investment securities:
Taxable	21,214	19,006
Tax-exempt	2,195	2,491
Other interest income	165	83
Total interest income	111,407	96,981
Interest expense:
Savings deposits	2,228	1,289
Time deposits	2,669	2,376
Securities sold under repurchase agreements	1,023	3,068
Other borrowings	4,689	1,263
Junior subordinated deferrable interest debentures	1,526	1,250
Total interest expense	12,135	9,246
Net interest income	99,272	87,735
Provision for probable loan losses	1,662	1,700
Net interest income after provision for probable loan losses	97,610	86,035
Non-interest income:
Investment securities transactions, net		927
Other investments, net	4,726	4,268
Other income	4,055	2,894
Total non-interest income	38,975	37,715
Non-interest expense:
Employee compensation and benefits	34,618	32,730
Occupancy	6,075	5,991
Depreciation of bank premises and equipment	6,273	6,227
Professional fees	2,572	3,716
Deposit insurance assessments	1,000	390
Net expense, other real estate owned	(271)	914
Amortization of identified intangible assets		25
Advertising	1,839	2,268
Early termination fee - securities sold under repurchase agreements		5,765
Software and software maintenance	4,072	3,791
Other	12,731	13,809
Total non-interest expense	68,909	75,626
Income before income taxes	67,676	48,124
Provision for income taxes	14,256	16,120
Net income	$ 53,420	$ 32,004
Basic earnings per common share:
Weighted average number of shares outstanding (in shares)	66,092,379	65,994,201
Net income (in dollars per share)	$ 0.81	$ 0.48
Fully diluted earnings per common share:
Weighted average number of shares outstanding (in shares)	66,863,895	66,747,499
Net income (in dollars per share)	$ 0.80	$ 0.48
Services charges on deposit accounts
Non-interest income:
Service charges	$ 17,712	$ 17,906
Other service charges, commissions and fees, Banking
Non-interest income:
Service charges	11,122	10,385
Other service charges, commissions and fees, Non-banking
Non-interest income:
Service charges	$ 1,360	$ 1,335