Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating Activities:
Net income	$ 99,102	$ 116,015
Adjustments to reconcile net income to net cash from operating activities:
Credit loss expense	0	63
Deferred tax expense (benefit)	(432)	4,172
Accretion of loan discounts	(2,945)	(3,425)
Securities premium amortization (discount accretion), net	27,654	30,598
Net (gain) loss on securities transactions	0	0
Depreciation and amortization	17,551	16,941
Net (gain) loss on sale/write-down of assets/foreclosed assets	130	(134)
Stock-based compensation	2,112	2,526
Net tax benefit from stock-based compensation	1,244	3,136
Earnings on life insurance policies	(533)	(740)
Net change in:
Trading account securities	139	(2,153)
Lease right-of-use assets	5,970	5,889
Accrued interest receivable and other assets	(55,232)	73,164
Accrued interest payable and other liabilities	238,065	(26,287)
Net cash from operating activities	332,825	219,765
Investing Activities:
Securities held-to-maturity - Purchases	(31,545)	0
Securities held to maturity: Maturities, calls and principal repayments	111,211	120,029
Securities available for sale:
Purchases	(3,356,279)	(455,091)
Sales	0	0
Maturities, calls and principal repayments	236,032	351,612
Net change in loans	(209,490)	(406,836)
Benefits received on life insurance policies	1,201	968
Proceeds from sales of premises and equipment	1	3
Purchases of premises and equipment	(12,374)	(12,814)
Proceeds from sales of repossessed properties	1,543	100
Net cash from investing activities	(3,259,700)	(402,029)
Financing Activities:
Net change in deposits	1,735,233	1,909,419
Net change in short-term borrowings	(888,906)	(193,573)
Proceeds from stock option exercises	5,739	29,397
Purchase of treasury stock	(996)	(1,288)
Cash dividends paid on preferred stock	(1,669)	(2,151)
Cash dividends paid on common stock	(48,443)	(46,124)
Net cash from financing activities	800,958	1,695,680
Net change in cash and cash equivalents	(2,125,917)	1,513,416
Cash and cash equivalents at beginning of period	16,583,000	10,288,853
Cash and cash equivalents at end of period	$ 14,457,083	$ 11,802,269