Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 235,248	$ 227,530
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22,867	19,740
Provision for loan losses	38,552	28,016
(Gain) loss on other real estate and foreclosed assets	852	(313)
Deferred tax expense	30,136	20,342
Increase in cash surrender value of life insurance contracts	(10,792)	(6,714)
Loss on disposal of other assets	70	1,748
Loss on sale of business		1,145
Net (increase) decrease in loans held for sale	(46,727)	10,942
Net amortization of securities premium/discount	23,133	25,440
Amortization of intangible assets	15,074	16,578
Stock-based compensation expense	15,497	14,868
Contribution to pension plan	(100,000)
Decrease in interest payable and other liabilities	(44,132)	(2,662)
Decrease in payable to FDIC for loan servicing		(11,113)
Increase in other assets	(10,631)	(15,748)
Other, net	(2,854)	299
Net cash provided by operating activities	166,293	330,098
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from the sale of securities available for sale	143,334
Proceeds from maturities of securities available for sale	204,391	253,755
Purchases of securities available for sale	(810,198)	(365,529)
Proceeds from maturities of securities held to maturity	297,150	272,986
Purchases of securities held to maturity	(183,626)	(375,770)
Net (increase) decrease in short-term investments	383,970	(15,690)
Proceeds from sales of loans and leases	111,141	47,481
Net increase in loans	(353,971)	(706,989)
Purchase of life insurance contracts	(32,788)	(1,601)
Purchases of property and equipment	(33,746)	(32,583)
Proceeds from sales of other real estate	20,764	10,114
Cash acquired in stock-based business combination	28,060
Consideration (paid) received in business combination	(1,112)	141,769
Proceeds from the sale of business, net of cash sold		77,648
Other, net	(19,815)	(50,935)
Net cash used in investing activities	(246,446)	(745,344)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net decrease in deposits	(229,964)	(52,709)
Net increase in short-term borrowings	452,691	572,757
Repayments of long-term debt	(226)	(90,142)
Net proceeds from issuance of long-term debt	11,649	124
Dividends paid	(70,771)	(65,287)
Payroll tax remitted on net share settlement of equity awards	(1,594)	(563)
Proceeds from exercise of stock options	367	1,232
Proceeds from dividend reinvestment and stock purchase plans	2,692	2,495
Net cash provided by financing activities	164,844	367,907
NET INCREASE (DECREASE) IN CASH AND DUE FROM BANKS	84,691	(47,339)
CASH AND DUE FROM BANKS, BEGINNING	383,372	386,948
CASH AND DUE FROM BANKS, ENDING	468,063	339,609
SUPPLEMENTAL INFORMATION FOR NON-CASH INVESTING AND FINANCING ACTIVITIES
Value of stock-based consideration in business combination	193,849
Assets acquired in settlement of loans	$ 14,170	$ 19,542