Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
OPERATING ACTIVITIES
Net income	$ 230,718	$ 193,522
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	16,948	16,043
Deferred tax expense (benefit)	5,126	(2,835)
Net change in current taxes	(23,826)	(16,609)
Depreciation	50,574	47,343
Net (decrease) increase in accrued interest payable	10,485	(2,043)
Net (increase) decrease in income earned not collected	(1,747)	(1,601)
Securities gains, net	(5,719)	0
Marketable equity securities gain (loss), net	(14,472)	(5,411)
Gain on extinguishment of debt	0	(25,814)
Origination of loans held for sale	(328,481)	(304,580)
Proceeds from sale of loans held for sale	326,640	302,766
Gain on sale of loans held for sale	(6,096)	(5,610)
Gain on sale of portfolio loans	(299)	0
Net writedowns/losses on other real estate	1,417	2,698
(Gain) loss on sales of premises and equipment	716	991
Net accretion of premiums and discounts	(19,765)	(17,240)
Amortization of intangible assets	12,019	11,562
Net change in FDIC payable for shared-loss agreements	3,274	2,145
Net change in mortgage servicing rights	(2,283)	(2,630)
Net change in other assets	(13,091)	313,265
Net change in other liabilities	(22,373)	14,998
Net cash provided by operating activities	219,765	520,960
INVESTING ACTIVITIES
Net increase in loans outstanding	(168,572)	(360,764)
Purchases of investment securities available for sale	(1,553,876)	(920,357)
Purchases of investment securities held to maturity	(183,288)	0
Purchases of marketable equity securities	(14,108)	(2,818)
Proceeds from maturities/calls of investment securities held to maturity	190,644	78,384
Proceeds from maturities/calls of investment securities available for sale	1,061,895	797,739
Proceeds from sales of investment securities available for sale	610,787	119,273
Proceeds from sales of marketable equity securities	10,694	8,493
Net decrease (increase) in overnight investments	(840,371)	175,009
Proceeds from sales of portfolio loans	24,247	0
Proceeds from sales of other real estate	11,884	15,769
Proceeds from sales of premises and equipment	75	198
Purchases of premises and equipment	(54,873)	(60,594)
Business acquisitions, net of cash acquired	(73,792)	(106,298)
Net cash used in investing activities	(978,654)	(255,966)
FINANCING ACTIVITIES
Net decrease in time deposits	291,930	(181,889)
Net increase in demand and other interest-bearing deposits	762,021	704,909
Net decrease in short-term borrowings	(109,109)	(201,303)
Repayment of long-term obligations	(33,008)	(653,929)
Repurchase of common stock	(186,995)	0
Cash dividends paid	(9,243)	(8,407)
Net cash (used in) provided by financing activities	715,596	(340,619)
Change in cash and due from banks	(43,293)	(75,625)
Cash and due from banks at beginning of period	327,440	336,150
Cash and due from banks at end of period	284,147	260,525
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Transfers of loans to other real estate	5,710	11,868
Dividends declared but not paid	4,410	4,204
Unsettled maturities of investment securities	150,122	0
Unsettled purchases of investment securities	1,126	0
Reclassification of portfolio loans to loans held for sale	(23,948)	0
Reclassification of loans held for sale to portfolio	605	0
Transfers of premises and equipment to other real estate	2,184	0
Transfer of investment securities available for sale to held to maturity	0	2,486,761
Unsettled common stock repurchases	3,535	0
Initial recognition of operating lease assets	70,652	0
Initial recognition of operating lease liabilities	$ 71,793	$ 0