Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES
Net income	$ 170,059	$ 135,144
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	22,750	35,000
Net accretion of premiums and discounts from acquisition	(193)	(1,810)
Depreciation and amortization	39,781	41,538
Deferred income tax (benefit) expense	(22,535)	1,555
Net increase in trading securities and other earning assets	(29,583)	(17,680)
Gains on sales of securities available for sale, net	(578)	(4,138)
Gains on sales of assets	(157)	(484)
Amortization of securities premiums, net of discount accretion	33,906	36,571
Originations of loans held for sale	(40,836)	(53,207)
Gains on sales of loans held for sale, net	(966)	(1,188)
Proceeds from sales of loans held for sale	41,040	55,149
Equity-based compensation	8,964	10,047
Net tax benefit related to equity compensation plans	2,241	3,149
Changes in:
Accrued income	(5,149)	(4,031)
Accrued expenses and taxes	(19,916)	21,011
Other assets and liabilities, net	25,258	(12,336)
Net cash provided by operating activities	224,086	244,290
INVESTING ACTIVITIES
Proceeds from maturities of securities held to maturity	81,670	64,079
Proceeds from sales of securities available for sale	95,525	573,062
Proceeds from maturities of securities available for sale	825,504	1,005,585
Purchases of securities held to maturity	(20,159)	(225,445)
Purchases of securities available for sale	(760,205)	(1,107,842)
Net increase in loans	(708,880)	(481,593)
Net (increase) decrease in fed funds sold and resell agreements	(14,811)	79,891
Net cash activity from acquisitions and divestitures	2,364	(2,532)
Net (increase) decrease in interest bearing balances due from other financial institutions	(4,776)	34,164
Purchases of premises and equipment	(36,731)	(24,748)
Proceeds from sales of premises and equipment	463	1,650
Increase in COLI/BOLI cash surrender value		(62,800)
Proceeds from bank-owned life insurance death benefit	16
Net cash used in investing activities	(540,020)	(146,529)
FINANCING ACTIVITIES
Net decrease in demand and savings deposits	(46,544)	(559,697)
Net decrease in time deposits	(239,752)	(11,313)
Net decrease in fed funds purchased and repurchase agreements	(67,719)	(100)
Repayment of long-term debt	(1,554)	(1,491)
Cash dividends paid	(43,529)	(38,171)
Proceeds from exercise of stock options and sales of treasury shares	9,880	11,629
Purchases of treasury stock	(26,417)	(14,369)
Net cash used in financing activities	(415,635)	(613,512)
Decrease in cash and cash equivalents	(731,569)	(515,751)
Cash and cash equivalents at beginning of period	1,716,262	1,063,967
Cash and cash equivalents at end of period	984,693	548,216
Supplemental Disclosures:
Income taxes paid	62,776	37,109
Total interest paid	$ 76,066	$ 40,245