Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities
Net income per consolidated statements of income	$ 121,143	$ 108,808
Adjustments to reconcile net income to net cash provided by operating activities:
Credit loss expense, net	(22,872)	50,547
Depreciation and amortization	34,337	30,000
Net amortization of securities	15,527	8,458
Gains on sales of loans, net	(58,905)	(61,464)
Compensation expense, long-term incentive plan	4,511	3,907
Deferred income tax provision	18,750	(20,600)
Proceeds from sales of loans held for sale	1,854,487	1,869,187
Purchases and originations of loans held for sale	(1,737,168)	(1,976,190)
Originations of mortgage servicing rights	(22,015)	(20,728)
Earnings on bank-owned life insurance	(3,633)	(3,845)
Net change in other assets	39,808	(53,141)
Net change in other liabilities	10,781	5,667
Other operating activities, net	(7,551)	30,367
Net cash from operating activities	247,200	(29,027)
Investing Activities
Proceeds from maturities, prepayments and calls of securities held to maturity	144,356	128,367
Proceeds from maturities, prepayments and calls of securities available for sale	635,138	465,568
Purchases of securities available for sale	(1,743,290)	(758,008)
Net proceeds from bank-owned life insurance	1,791	592
Net change in federal funds sold and securities purchased under reverse repurchase agreements	50	(50)
Net change in member bank stock	(1,217)	281
Net change in LHFI and PPP loans	(137,919)	(1,384,833)
Proceeds from sales of PPP loans	353,287	0
Purchases of premises and equipment	(19,499)	(15,634)
Proceeds from sales of premises and equipment	741	548
Proceeds from sales of other real estate	3,611	11,434
Purchases of software	(2,926)	(6,050)
Investments in tax credit and other partnerships	(14,690)	(4,458)
Purchase of insurance book of business	0	(3,097)
Net cash used in business acquisition	0	(4,834)
Net cash from investing activities	(780,567)	(1,570,174)
Financing Activities
Net change in deposits	874,075	1,976,856
Net change in federal funds purchased and securities sold under repurchase agreements	(18,102)	(102,186)
Net change in short-term borrowings	(19,171)	4,272
Payments on long-term FHLB advances	(14)	(39)
Payments under finance lease obligations	(1,072)	(1,319)
Common stock dividends	(43,800)	(44,079)
Repurchase and retirement of common stock	(34,658)	(27,538)
Shares withheld to pay taxes, long-term incentive plan	(1,337)	(1,094)
Net cash from financing activities	755,921	1,804,873
Net change in cash and cash equivalents	222,554	205,672
Cash and cash equivalents at beginning of period	1,952,504	358,916
Cash and cash equivalents at end of period	$ 2,175,058	$ 564,588