Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Cash and cash equivalents:
Cash and due from banks	$ 478,271	$ 510,922
Federal funds sold and interest-earning deposits with banks	493,378	236,435
Deposits in other financial institutions (restricted cash)	237,808	251,520
Total cash and cash equivalents	1,209,457	998,877
Trading securities, at fair value	66,188	31,321
Investment securities:
Securities held to maturity (fair value of $2,016,567 and $2,084,736)	2,446,589	2,487,440
Securities available for sale, at fair value	4,598,400	4,784,388
Other investments	187,285	192,043
Total investment securities	7,232,274	7,463,871
Loans held for sale	56,553	50,888
Loans:
Total loans	32,667,310	32,388,489
Less allowance for credit losses	(469,654)	(456,573)
Loans, net	32,197,656	31,931,916
Premises and equipment, net	512,635	519,197
Bank owned life insurance ("BOLI")	997,562	991,454
Deferred tax assets	170,818	164,354
Derivatives assets	176,784	172,939
Mortgage servicing rights	87,970	85,164
Core deposit and other intangibles	83,193	88,776
Goodwill	1,923,106	1,923,106
Other assets	430,642	480,161
Total assets	45,144,838	44,902,024
Deposits:
Noninterest-bearing	10,546,410	10,649,274
Interest-bearing	26,632,024	26,399,635
Total deposits	37,178,434	37,048,909
Federal funds purchased	273,367	248,162
Securities sold under agreements to repurchase	281,324	241,023
Corporate and subordinated debentures	391,812	391,904
Other borrowings		100,000
Reserve for unfunded commitments	53,229	56,303
Derivative liabilities	954,788	804,486
Other liabilities	464,875	478,139
Total liabilities	39,597,829	39,368,926
Shareholders' equity:
Common stock - $2.50 par value; authorized 160,000,000 shares; 76,177,163 and 76,022,039 shares issued and outstanding, respectively	190,443	190,055
Surplus	4,230,345	4,240,413
Retained earnings	1,749,215	1,685,166
Accumulated other comprehensive loss	(622,994)	(582,536)
Total shareholders' equity	5,547,009	5,533,098
Total liabilities and shareholders' equity	45,144,838	44,902,024
Acquired - non-purchased credit deteriorated loans
Loans:
Total loans	4,534,583	4,796,913
Acquired - purchased credit deteriorated loans
Loans:
Total loans	1,031,283	1,108,813
Non-acquired loans
Loans:
Total loans	$ 27,101,444	$ 26,482,763