Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
OPERATING ACTIVITIES
Net income	$ 112,210	$ 87,002
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	17,000	23,500
Net accretion of premiums and discounts from acquisition	(184)	(1,691)
Depreciation and amortization	26,544	28,535
Deferred income tax benefit	(34,703)	(1,737)
Net increase in trading securities and other earning assets	(14,742)	(19,209)
Gains on sales of securities available for sale, net	(367)	(1,748)
Losses on sales of assets	212	19
Amortization of securities premiums, net of discount accretion	22,647	24,139
Originations of loans held for sale	(25,502)	(32,809)
Gains on sales of loans held for sale, net	(550)	(745)
Proceeds from sales of loans held for sale	24,030	35,390
Equity-based compensation	5,695	6,715
Net tax benefit related to equity compensation plans	2,059	3,100
Changes in:
Accrued income	(1,270)	(77)
Accrued expenses and taxes	(43,856)	(11,497)
Other assets and liabilities, net	9,592	(19,640)
Net cash provided by operating activities	98,815	119,247
INVESTING ACTIVITIES
Proceeds from maturities of securities held to maturity	66,253	32,812
Proceeds from sales of securities available for sale	41,272	271,824
Proceeds from maturities of securities available for sale	599,647	741,395
Purchases of securities held to maturity	(10,307)	(197,425)
Purchases of securities available for sale	(515,636)	(733,530)
Net increase in loans	(373,358)	(322,944)
Net decrease in fed funds sold and resell agreements	121,255	139,806
Net cash activity from acquisitions and divestitures	2,874	(1,954)
Net decrease in interest bearing balances due from other financial institutions	7,336	24,285
Purchases of premises and equipment	(22,152)	(11,323)
Proceeds from sales of premises and equipment	26	33
Proceeds from bank-owned life insurance death benefit	16
Net cash used in investing activities	(82,774)	(57,021)
FINANCING ACTIVITIES
Net decrease in demand and savings deposits	(1,276,612)	(572,374)
Net (decrease) increase in time deposits	(360,310)	98,426
Net increase in fed funds purchased and repurchase agreements	405,454	29,433
Repayment of long-term debt	(1,138)	(1,226)
Cash dividends paid	(29,062)	(25,456)
Proceeds from exercise of stock options and sales of treasury shares	7,999	10,833
Purchases of treasury stock	(6,211)	(4,279)
Net cash used in financing activities	(1,259,880)	(464,643)
Decrease in cash and cash equivalents	(1,243,839)	(402,417)
Cash and cash equivalents at beginning of period	1,716,262	1,063,967
Cash and cash equivalents at end of period	472,423	661,550
Supplemental Disclosures:
Income taxes paid	51,701	20,679
Total interest paid	$ 43,901	$ 23,633