Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
OPERATING ACTIVITIES
Net income	$ 57,744	$ 56,786
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	12,350	10,000
Net amortization (accretion) of premiums and discounts from acquisition	135	(10)
Depreciation and amortization	13,614	13,371
Deferred income tax expense (benefit)	295	(7,760)
Net decrease (increase) in trading securities and other earning assets	4,507	(13,628)
Gains on sales of securities available for sale, net	(809)	(139)
(Gains) losses on sales of assets	(236)	142
Amortization of securities premiums, net of discount accretion	8,859	11,640
Originations of loans held for sale	(19,156)	(12,520)
Gains on sales of loans held for sale, net	(177)	(270)
Proceeds from sales of loans held for sale	21,258	9,664
Equity-based compensation	3,893	2,765
Net tax benefit related to equity compensation plans	539	1,713
Changes in:
Accrued income	(6,839)	1,231
Accrued expenses and taxes	(13,319)	(61,711)
Other assets and liabilities, net	(36,453)	8,345
Net cash provided by operating activities	46,205	19,619
INVESTING ACTIVITIES
Proceeds from maturities of securities held to maturity	22,769	21,303
Proceeds from sales of securities available for sale	53,329	41,273
Proceeds from maturities of securities available for sale	267,255	328,267
Purchases of securities held to maturity	(1,893)	(6,756)
Purchases of securities available for sale	(579,392)	(340,795)
Net increase in loans	(383,799)	(188,349)
Net decrease in fed funds sold and resell agreements	362,229	64,393
Net cash activity from acquisitions and divestitures		2,874
Net (increase) decrease in interest bearing balances due from other financial institutions	(3,867)	6,674
Purchases of premises and equipment	(10,066)	(8,639)
Proceeds from sales of premises and equipment	2,904
Net cash used in investing activities	(270,531)	(79,755)
FINANCING ACTIVITIES
Net increase (decrease) in demand and savings deposits	332,490	(511,650)
Net decrease in time deposits	(248,535)	(293,085)
Net (decrease) increase in fed funds purchased and repurchase agreements	(24,872)	93,911
Repayment of long-term debt	(1,305)	(898)
Cash dividends paid	(14,777)	(14,531)
Proceeds from exercise of stock options and sales of treasury shares	1,448	5,532
Purchases of treasury stock	(4,086)	(5,951)
Net cash provided by (used in) financing activities	40,363	(726,672)
Decrease in cash and cash equivalents	(183,963)	(786,808)
Cash and cash equivalents at beginning of period	1,674,121	1,716,262
Cash and cash equivalents at end of period	1,490,158	929,454
Supplemental Disclosures:
Income tax (refunds) payments	(12)	5,972
Total interest payments	$ 39,524	$ 19,168