Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
OPERATING ACTIVITIES
Net income	$ 355,497	$ 310,840
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	23,714	16,883
Deferred tax expense (benefit)	43,939	13,642
Net change in current taxes	(33,433)	(21,266)
Depreciation	77,024	71,484
Net (decrease) increase in accrued interest payable	14,147	(1,552)
Net (increase) decrease in income earned not collected	(3,567)	(7,650)
Realized gains on investment securities available for sale, net	(6,855)	0
Marketable equity securities gain (loss), net	(13,505)	(9,265)
Gain on extinguishment of debt	0	(26,517)
Origination of loans held for sale	(518,894)	(456,193)
Proceeds from sale of loans held for sale	490,261	468,705
Gain on sale of loans held for sale	(10,308)	(8,640)
Gain on sale of portfolio loans	(299)	0
Net writedowns/losses on other real estate	1,924	3,156
(Gain) loss on sales of premises and equipment	1,082	1,480
Net accretion of premiums and discounts	(29,737)	(22,965)
Amortization of intangible assets	17,934	17,580
Net change in FDIC payable for shared-loss agreements	4,968	3,234
Net change in mortgage servicing rights	(3,770)	(4,026)
Net change in other assets	1,454	34,851
Net change in other liabilities	(12,416)	(53,708)
Net cash provided by operating activities	399,160	330,073
INVESTING ACTIVITIES
Net increase in loans outstanding	(629,705)	(702,356)
Purchases of investment securities available for sale	(3,706,949)	(979,495)
Purchases of investment securities held to maturity	(223,353)	(68,699)
Purchases of marketable equity securities	(23,238)	(2,818)
Proceeds from maturities/calls of investment securities held to maturity	305,479	196,146
Proceeds from maturities/calls of investment securities available for sale	1,690,277	1,046,293
Proceeds from sales of investment securities available for sale	1,746,099	327,737
Proceeds from sales of marketable equity securities	12,739	9,503
Net decrease (increase) in overnight investments	(150,006)	455,295
Proceeds from sales of portfolio loans	24,247	0
Proceeds from sales of other real estate	18,892	23,488
Proceeds from sales of premises and equipment	128	1,648
Purchases of premises and equipment	(89,219)	(91,200)
Business acquisitions, net of cash acquired	(73,792)	(106,298)
Net cash used in investing activities	(1,098,401)	109,244
FINANCING ACTIVITIES
Net decrease in time deposits	376,596	(218,826)
Net increase in demand and other interest-bearing deposits	701,426	496,499
Net decrease in short-term borrowings	(138,741)	(127,547)
Repayment of long-term obligations	(43,545)	(717,370)
Origination of long-term obligations	100,000	125,000
Repurchase of common stock	(321,263)	(58,086)
Cash dividends paid	(13,739)	(12,612)
Net cash (used in) provided by financing activities	660,734	(512,942)
Change in cash and due from banks	(38,507)	(73,625)
Cash and due from banks at beginning of period	327,440	336,150
Cash and due from banks at end of period	288,933	262,525
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Transfers of loans to other real estate	13,242	17,013
Dividends declared but not paid	4,397	4,168
Net reclassification of portfolio loans to (from) loans held for sale	(22,758)	2,016
Transfers of premises and equipment to other real estate	2,184	0
Transfer of investment securities available for sale to held to maturity	0	2,485,761
Unsettled common stock repurchases	4,653	0
Initial recognition of operating lease assets	70,652	0
Initial recognition of operating lease liabilities	$ 71,793	$ 0