Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities:
Net income	$ 242,881	$ 339,918
Adjustments to reconcile net income to net cash from operating activities:
Credit loss expense	227,474	25,404
Deferred tax expense (benefit)	(8,803)	(1,625)
Accretion of loan discounts	(11,905)	(11,364)
Securities premium amortization (discount accretion), net	93,080	84,963
Net (gain) loss on securities transactions	(108,989)	(265)
Depreciation and amortization	47,752	39,182
Net (gain) loss on sale/write-down of assets/foreclosed assets	(6)	(6,016)
Stock-based compensation	8,227	10,693
Net tax benefit from stock-based compensation	694	1,602
Earnings on life insurance policies	(2,895)	(2,744)
Net change in:
Trading account securities	(197)	(3,132)
Lease right-of-use assets	17,419	14,618
Accrued interest receivable and other assets	(52,842)	37,608
Accrued interest payable and other liabilities	23,208	56,354
Net cash from operating activities	475,098	585,196
Investing Activities:
Securities held-to-maturity - Purchases	(1,500)	0
Securities held to maturity: Maturities, calls and principal repayments	63,333	69,273
Securities available for sale:
Purchases	(8,324,364)	(9,815,936)
Sales	1,162,352	8,236,066
Maturities, calls and principal repayments	8,162,036	1,007,783
Proceeds from sale of loans	0	24,036
Net change in loans	(3,551,650)	(569,223)
Benefits received on life insurance policies	903	0
Proceeds from sales of premises and equipment	3,054	8,019
Purchases of premises and equipment	(81,866)	(168,326)
Proceeds from sales of repossessed properties	73	131
Net cash from investing activities	(2,567,629)	(1,208,177)
Financing Activities:
Net change in deposits	5,859,939	(65,622)
Net change in short-term borrowings	(86,675)	(166,893)
Proceeds from Federal Home Loan Bank advances	1,250,000	0
Principal payments on Federal Home Loan Bank advances	(1,250,000)	0
Redemption of preferred stock	(150,000)	0
Proceeds from stock option exercises	7,544	13,506
Purchase of treasury stock	(14,000)	(67,709)
Cash dividends paid on preferred stock	(2,016)	(6,047)
Cash dividends paid on common stock	(134,762)	(132,132)
Net cash from financing activities	5,480,030	(424,897)
Net change in cash and cash equivalents	3,387,499	(1,047,878)
Cash and cash equivalents at beginning of period	3,788,181	3,955,779
Cash and cash equivalents at end of period	$ 7,175,680	$ 2,907,901