Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Cash and cash equivalents:
Cash and due from banks	$ 344,389	$ 262,019	$ 258,357
Federal funds sold and interest-bearing deposits with banks	3,199,101	377,692	396,804
Deposits in other financial institutions (restricted cash)	928,149	48,993	64,033
Total cash and cash equivalents	4,471,639	688,704	719,194
Investment securities:
Securities available for sale, at fair value (cost of $3,498,087 and allowance for credit losses of $0 for September 30, 2020)	3,561,929	1,956,047	1,813,134
Other investments	185,199	49,124	49,124
Total investment securities	3,747,128	2,005,171	1,862,258
Loans held for sale	456,141	59,363	87,393
Loans:
Total loans - ASU 2016-13	25,237,815
Total loans		11,375,104	11,290,147
Less allowance for credit losses	(440,159)	(56,927)	(54,937)
Loans, net	24,797,656	11,313,113	11,229,892
Other real estate owned	13,480	6,539	8,424
Bank property held for sale	24,504	5,425	4,991
Premises and equipment, net	626,259	317,321	323,506
Bank owned life insurance	556,475	234,567	233,206
Deferred tax assets	107,500	31,316	27,844
Derivatives assets	953,036	15,463	24,316
Mortgage servicing rights	34,578	30,525	28,674
Core deposit and other intangibles	171,637	49,816	53,083
Goodwill	1,566,524	1,002,900	1,002,900
Other assets	292,809	160,869	146,401
Total assets	37,819,366	15,921,092	15,752,082
Deposits:
Noninterest-bearing	9,681,095	3,245,306	3,307,532
Interest-bearing	20,288,859	8,931,790	8,716,255
Total deposits	29,969,954	12,177,096	12,023,787
Federal funds purchased	351,676	56,581	33,539
Securities sold under agreements to repurchase	355,047	242,160	235,533
Corporate and subordinated debentures	389,540	115,833	115,666
Other borrowings	700,097	700,103	700,105
Reserve for unfunded commitments	43,161	335	335
Derivative liabilities	979,155	30,485	43,287
Other liabilities	467,323	225,486	248,874
Total liabilities	33,255,953	13,548,079	13,401,126
Shareholders' equity:
Common stock - $2.50 par value; authorized 160,000,000, 80,000,000 and 80,000,000 shares; 70,928,304, 33,744,385 and 33,902,726 shares issued and outstanding, respectively	177,321	84,361	84,757
Surplus	3,764,482	1,607,740	1,617,004
Retained earnings	604,564	679,895	646,325
Accumulated other comprehensive income	17,046	1,017	2,870
Total shareholders' equity	4,563,413	2,373,013	2,350,956
Total liabilities and shareholders' equity	37,819,366	15,921,092	15,752,082
Acquired - non-purchased credit deteriorated loans
Loans:
Total loans - ASU 2016-13	10,557,907
Total loans		1,760,427	1,965,603
Acquired - purchased credit deteriorated loans (formerly acquired credit-impaired loans)
Loans:
Total loans - ASU 2016-13	3,143,822
Total loans		356,782	390,714
Non-acquired loans
Loans:
Total loans - ASU 2016-13	$ 11,536,086
Total loans		9,252,831	8,928,512
Less allowance for credit losses		(56,927)	(54,937)
Loans, net		$ 9,195,904	$ 8,873,575