Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES
Net income	$ 100,231	$ 67,621
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	7,605	8,231
Deferred tax expense (benefit)	(5,573)	6,693
Net change in current taxes	33,128	27,462
Depreciation	23,179	22,616
Net increase (decrease) in accrued interest payable	(2,454)	150
Net (increase) decrease in income earned not collected	(1,358)	(617)
Gain on acquisitions	0	(12,017)
Securities (gains) losses, net	0	24
Marketable equity securities gain (loss), net	(971)	0
Gain on extinguishment of debt	(25,814)	0
Loss on termination of FDIC shared-loss agreements	0	45
Origination of loans held for sale	(131,353)	(134,932)
Proceeds from sale of loans held for sale	138,538	162,837
Gain on sale of loans held for sale	(2,666)	(3,456)
(Gain) loss on sale of portfolio loans	0	(164)
Net writedowns/losses on other real estate	1,210	1,717
(Gain) loss on sales of premises and equipment	0	(156)
Net accretion of premiums and discounts	(10,323)	(10,985)
Amortization of intangible assets	6,049	5,271
Reduction FDIC receivable for shared-loss agreements	(1,834)	2,591
Net increase (decrease) in FDIC payable for shared-loss agreements	1,124	1,005
Net change in other assets	342,312	(15,078)
Net change in other liabilities	(12,642)	8,741
Net cash provided by operating activities	458,388	137,599
INVESTING ACTIVITIES
Net change in loans outstanding	(7,283)	(105,100)
Purchases of investment securities available for sale	(374,850)	(871,698)
Payments to Acquire Marketable Securities	(2,272)	0
Proceeds from maturities of investment securities held to maturity	2	15
Proceeds from maturities of investment securities available for sale	503,717	787,182
Proceeds from sales of investment securities available for sale	0	14,162
Proceeds from Sale and Maturity of Marketable Securities	664	0
Net change in overnight investments	(558,955)	(856,442)
Proceeds from sales of portfolio loans	0	32,294
Cash (paid to) received from the FDIC for shared-loss agreements	0	(2,760)
Net payment to the FDIC for termination of shared-loss agreements	0	(285)
Proceeds from sale of other real estate	8,380	8,845
Proceeds fro sales of premises and equipment	13	2,205
Additions to premises and equipment	(24,081)	(15,459)
Net cash acquired in business acquisitions	0	25,646
Net cash (used) provided by investing activities	(454,665)	(981,395)
FINANCING ACTIVITIES
Net change in time deposits	(92,064)	(107,339)
Net change in demand and other interest-bearing deposits	795,034	827,009
Net change in short-term borrowings	(139,049)	87,100
Repayment of long-term obligations	(651,451)	(442)
Cash dividends paid	(4,204)	0
Net cash provided (used) by financing activities	(91,734)	806,328
Change in cash and due from banks	(88,011)	(37,468)
Cash and due from banks at beginning of period	336,150	539,741
Cash and due from banks at end of period	248,139	502,273
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Transfers of loans to other real estate	6,582	5,822
Dividends declared but not paid	4,204	3,603
Transfer of Portfolio Loans and Leases to Held-for-sale	$ 0	$ 32,130