Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Interest income
Interest and fees on loans	$ 179,311	$ 175,130	$ 338,165	$ 340,001
Interest on federal funds sold and other short-term investments	1,868	5,405	5,833	11,242
Interest and dividends on securities:
Taxable	16,241	17,748	33,210	35,111
Tax-exempt	1,297	962	1,991	1,988
Total interest income	198,717	199,245	379,199	388,342
Interest expense
Interest on deposits	19,249	35,455	46,726	68,093
Interest on short-term borrowings	196	608	654	1,299
Interest on long-term borrowings	8,670	12,629	19,699	24,229
Total interest expense	28,115	48,692	67,079	93,621
Net interest income	170,602	150,553	312,120	294,721
Provision for credit losses	45,911	5,417	73,030	10,413
Net interest income after provision for credit losses	124,691	145,136	239,090	284,308
Other income
Income from bank-owned life insurance	1,291	1,326	3,679	3,153
Mortgage loan servicing income	1,534	0	1,534	0
Net investment securities gains (losses)	1,510	109	1,706	(50)
Other income	547	310	1,271	666
Total other income	88,390	39,795	125,196	71,018
Other expense
Employee compensation	68,664	44,301	113,205	83,250
Employee benefits	12,779	8,578	23,565	18,009
Net occupancy expense	10,318	8,667	19,380	17,418
Other real estate owned ("OREO") expense	607	633	1,513	2,049
Equipment expense	5,004	3,675	8,849	6,990
Data processing expense	15,926	5,567	21,432	10,729
Mortgage loan servicing expense and impairment	2,510	106	2,648	197
Bankcard processing expense	392	448	869	928
FDIC insurance expense	2,782	3,300	5,182	6,600
FHLB prepayment penalties	0	5,105	0	5,105
Other expense	30,392	19,815	53,864	38,345
Total other expense	149,374	100,195	250,507	189,620
Income before income taxes	63,707	84,736	113,779	165,706
Income taxes	11,021	17,529	20,910	34,857
Net income	$ 52,686	$ 67,207	$ 92,869	$ 130,849
Earnings per common share:
Basic	$ 0.44	$ 0.66	$ 0.84	$ 1.28
Diluted	$ 0.44	$ 0.66	$ 0.84	$ 1.28
Average outstanding shares:
Basic	119,823,652	101,773,643	110,559,363	101,833,880
Diluted	119,887,823	102,047,845	110,624,976	102,099,809
Fees From Trust Services [Member]
Other income
Revenue from contract	$ 3,261	$ 3,438	$ 6,744	$ 6,702
Fees from Brokerage Services [Member]
Other income
Revenue from contract	2,651	2,766	5,567	5,290
Fees from Deposit Services [Member]
Other income
Revenue from contract	8,055	8,464	16,012	16,517
Bankcard Fees and Merchant Discounts [Member]
Other income
Revenue from contract	718	1,102	1,711	2,258
Other Service Charges, Commissions, and Fees [Member]
Other income
Revenue from contract	610	576	1,128	1,097
Mortgage Banking [Member]
Other income
Revenue from contract	$ 68,213	$ 21,704	$ 85,844	$ 35,385