Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
OPERATING ACTIVITIES
Net income	$ 105,963	$ 92,643
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(6,500)	(7,500)
Net amortization of premiums and discounts from acquisition	379	117
Depreciation and amortization	13,152	14,042
Amortization of debt issuance costs	113	113
Deferred income tax (benefit) expense	(1,023)	10,246
Net decrease (increase) in trading securities and other earning assets	14,816	(9,350)
Losses on investment securities, net	522	8,336
Gains on sales of assets	(2,354)	(4,298)
Amortization of securities premiums, net of discount accretion	11,180	14,876
Originations of loans held for sale	(8,330)	(45,128)
Gains on sales of loans held for sale, net	(270)	(1,602)
Proceeds from sales of loans held for sale	9,493	43,163
Equity-based compensation	6,164	5,152
Net tax benefit related to equity compensation plans	2,369	1,079
Changes in:
Accrued income	3,860	4,156
Accrued expenses and taxes	(72,489)	(88,201)
Other assets and liabilities, net	119,007	78,096
Net cash provided by operating activities	196,052	115,940
Securities held to maturity:
Maturities, calls and principal repayments	70,091	49,520
Purchases	(334,546)	(77,576)
Securities available for sale:
Sales	0	129,128
Maturities, calls and principal repayments	439,293	520,441
Purchases	(540,925)	(1,322,855)
Equity securities with readily determinable fair values:
Sales	9,725
Purchases	(353)	(226)
Equity securities without readily determinable fair values:
Maturities, calls and principal repayments	6	2,177
Purchases	(11,323)	(7,144)
Payment on low-income housing tax credit investment commitments	(8,395)	(1,173)
Net increase in loans	(608,888)	(398,795)
Net (increase) decrease in fed funds sold and resell agreements	(103,452)	20,522
Net cash activity from acquisitions and divestitures	265,639	16,623
Net decrease (increase) in interest-bearing balances due from other financial institutions	14,368	(11,347)
Purchases of premises and equipment	(8,643)	(5,958)
Proceeds from sales of premises and equipment	2,968	73
Net cash used in investing activities	(814,435)	(1,086,590)
FINANCING ACTIVITIES
Net (decrease) increase in demand and savings deposits	(1,207,226)	1,441,071
Net decrease in time deposits	(264,608)	(211,530)
Net (decrease) increase in fed funds purchased and repurchase agreements	(397,900)	444,321
Cash dividends paid	(17,917)	(15,456)
Proceeds from exercise of stock options and sales of treasury shares	615	12,237
Purchases of treasury stock	(22,487)	(4,027)
Net cash (used in) provided by financing activities	(1,909,523)	1,666,616
(Decrease) increase in cash and cash equivalents	(2,527,906)	695,966
Cash and cash equivalents at beginning of period	9,214,564	3,497,566
Cash and cash equivalents at end of period	6,686,658	4,193,532
Supplemental disclosures:
Income tax payments	795	622
Total interest payments	13,043	$ 14,337
Noncash disclosures:
Acquisition of low-income housing tax credit investments	6,398
Commitment to fund low-income housing tax credit investments	6,398
Transfer of securities from available-for-sale to held-to-maturity	$ 2,857,187