Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating Activities:
Net income	$ 147,825	$ 228,082
Adjustments to reconcile net income to net cash from operating activities:
Credit loss expense	207,172	17,403
Deferred tax expense (benefit)	(51,933)	(675)
Accretion of loan discounts	(7,680)	(7,325)
Securities premium amortization (discount accretion), net	62,177	56,726
Net (gain) loss on securities transactions	(108,989)	(169)
Depreciation and amortization	31,489	25,705
Net (gain) loss on sale/write-down of assets/foreclosed assets	(139)	(5,135)
Stock-based compensation	5,784	8,018
Net tax benefit from stock-based compensation	556	1,131
Earnings on life insurance policies	(1,935)	(1,830)
Net change in:
Trading account securities	(197)	(1,068)
Lease right-of-use assets	11,491	9,167
Accrued interest receivable and other assets	(131,772)	(18,107)
Accrued interest payable and other liabilities	43,111	(20,008)
Net cash from operating activities	206,960	291,915
Investing Activities:
Securities held-to-maturity - Purchases	(1,500)	0
Securities held to maturity: Maturities, calls and principal repayments	51,232	60,077
Securities available for sale:
Purchases	(3,739,598)	(4,555,448)
Sales	1,162,352	3,291,529
Maturities, calls and principal repayments	3,791,908	708,273
Proceeds from sale of loans	0	24,036
Net change in loans	(3,293,619)	(390,452)
Proceeds from sales of premises and equipment	3,054	4,677
Purchases of premises and equipment	(52,036)	(98,622)
Proceeds from sales of repossessed properties	8	5
Net cash from investing activities	(2,078,199)	(955,925)
Financing Activities:
Net change in deposits	5,039,532	(1,164,181)
Net change in short-term borrowings	(105,958)	(48,041)
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	4,846	7,841
Purchase of treasury stock	(13,973)	(50,519)
Cash dividends paid on preferred stock	(2,016)	(4,031)
Cash dividends paid on common stock	(89,805)	(87,428)
Net cash from financing activities	4,682,626	(1,346,359)
Net change in cash and cash equivalents	2,811,387	(2,010,369)
Cash and cash equivalents at beginning of period	3,788,181	3,955,779
Cash and cash equivalents at end of period	$ 6,599,568	$ 1,945,410