Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 85,827	$ 82,785
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	16,837	18,025
Provision for loan losses	5,192	6,932
Deferred income taxes	1,457	5,517
(Gains) losses on sale of securities, net	(2,250)	641
Share-based compensation expense	4,357	4,353
Accretion of discount related to performing acquired loans	(6,518)	(17,251)
Loss on disposal of premises and equipment	3,723	1,266
Gain on sale of OREO	(380)	(204)
Net amortization of premiums on investment securities	3,325	3,843
OREO write downs	487	932
Fair value adjustment for loans held for sale	730	(208)
Originations and purchases of loans held for sale	(331,662)	(324,803)
Proceeds from sales of loans	306,062	358,929
Net change in:
Accrued interest receivable	(2,653)	(1,023)
Prepaid assets	(2,025)	(52)
Operating Leases	504
Miscellaneous other assets	(38,129)	8,819
Accrued interest payable	1,449	1,093
Accrued income taxes	470	6,404
Miscellaneous other liabilities	53,454	4,188
Net cash provided by operating activities	100,257	160,186
Cash flows from investing activities:
Proceeds from sales of investment securities available for sale	189,327	51,822
Proceeds from maturities and calls of investment securities held to maturity		2,030
Proceeds from maturities and calls of investment securities available for sale	113,039	114,825
Proceeds from sales of other investment securities	45	13,175
Purchases of investment securities available for sale	(463,473)	(130,378)
Purchases of other investment securities	(23,566)	(9,356)
Net increase in loans	(214,785)	(207,909)
Recoveries of loans previously charged off	1,949	2,104
Purchases of premises and equipment	(8,116)	(7,268)
Proceeds from sale of OREO	4,428	3,722
Proceeds from sale of premises and equipment	8	18
Net cash used in investing activities	(401,144)	(167,215)
Cash flows from financing activities:
Net increase in deposits	275,346	106,135
Net increase in federal funds purchased and securities sold under agreements to repurchase and other short-term borrowings	27,381	45,112
Proceeds from FHLB advances	700,001	260,001
Repayment of other borrowings	(150,004)	(360,003)
Common stock issuance	343	352
Common stock repurchase	(82,103)	(1,726)
Dividends paid on common stock	(27,491)	(24,651)
Stock options exercised	402	1,031
Net cash provided by financing activities	743,875	26,251
Net increase in cash and cash equivalents	442,988	19,222
Cash and cash equivalents at beginning of period	408,983	377,627
Cash and cash equivalents at end of period	851,971	396,849
Cash paid for:
Interest	41,476	20,152
Income taxes	20,903	11,796
Initial measurement and recognition of operating lease assets in exchange for lease liabilities per ASU 2016-02	82,160
Recognition of operating lease assets in exchange for lease liabilities	4,950
Acquisitions:
Fair value of tangible assets acquired		(7,068)
Other intangible assets acquired		3,321
Liabilities assumed		(612)
Net identifiable assets acquired over liabilities assumed		(3,135)
Real estate acquired in full or in partial settlement of loans	$ 7,632	$ 10,259