Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Cash and cash equivalents:
Cash and due from banks	$ 558,158	$ 548,387
Federal funds sold and interest-earning deposits with banks	1,215,766	580,491
Deposits in other financial institutions (restricted cash)	222,738	183,685
Total cash and cash equivalents	1,996,662	1,312,563
Trading securities, at fair value	16,039	31,263
Investment securities:
Securities held to maturity (fair value of $2,227,612 and $2,250,168)	2,636,673	2,683,241
Securities available for sale, at fair value	5,159,999	5,326,822
Other investments	217,991	179,717
Total investment securities	8,014,663	8,189,780
Loans held for sale	27,289	28,968
Loans:
Total loans	30,696,142	30,177,862
Less allowance for credit losses	(370,645)	(356,444)
Loans, net	30,325,497	29,821,418
Other real estate owned	3,473	1,023
Bank property held for sale	16,724	17,754
Premises and equipment, net	517,146	520,635
Bank owned life insurance ("BOLI")	967,750	964,708
Deferred tax assets	165,161	177,801
Derivatives assets	159,287	211,016
Mortgage servicing rights	85,406	86,610
Core deposit and other intangibles	109,603	116,450
Goodwill	1,923,106	1,923,106
Other assets	596,021	515,601
Total assets	44,923,827	43,918,696
Deposits:
Noninterest-bearing	12,422,583	13,168,656
Interest-bearing	23,979,009	23,181,967
Total deposits	36,401,592	36,350,623
Federal funds purchased	233,354	213,597
Securities sold under agreements to repurchase	310,754	342,820
Corporate and subordinated debentures	392,182	392,275
Other borrowings	900,000
Reserve for unfunded commitments	85,068	67,215
Derivative liabilities	806,584	1,034,143
Other liabilities	545,289	443,096
Total liabilities	39,674,823	38,843,769
Shareholders' equity:
Common stock - $2.50 par value; authorized 160,000,000 shares; 75,859,665 and 75,704,563 shares issued and outstanding, respectively	189,649	189,261
Surplus	4,224,503	4,215,712
Retained earnings	1,448,636	1,347,042
Accumulated other comprehensive loss	(613,784)	(677,088)
Total shareholders' equity	5,249,004	5,074,927
Total liabilities and shareholders' equity	44,923,827	43,918,696
Acquired - non-purchased credit deteriorated loans
Loans:
Total loans	5,620,290	5,943,092
Acquired - purchased credit deteriorated loans
Loans:
Total loans	1,325,400	1,429,731
Non-acquired loans
Loans:
Total loans	$ 23,750,452	$ 22,805,039