Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
OPERATING ACTIVITIES
Net income	$ 111,359	$ 100,231
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	11,750	7,605
Deferred tax expense (benefit)	(7,316)	(5,573)
Net change in current taxes	37,898	33,128
Depreciation	28,195	23,179
Net (decrease) increase in accrued interest payable	3,457	(2,454)
Net (increase) decrease in income earned not collected	(3,909)	(1,358)
Marketable equity securities gain (loss), net	(11,328)	(971)
Gain on extinguishment of debt	0	(25,814)
Origination of loans held for sale	(128,949)	(131,353)
Proceeds from sale of loans held for sale	123,047	138,538
Gain on sale of loans held for sale	(2,181)	(2,666)
Net writedowns/losses on other real estate	427	1,210
(Gain) loss on sales of premises and equipment	358	0
Net accretion of premiums and discounts	(8,737)	(10,323)
Amortization of intangible assets	5,943	6,049
Net change in FDIC payable for shared-loss agreements	1,638	1,124
Net change in mortgage servicing rights	(698)	(1,200)
Net change in other assets	31,072	341,678
Net change in other liabilities	(51,985)	(12,642)
Net cash provided by operating activities	140,041	458,388
INVESTING ACTIVITIES
Net increase in loans outstanding	68,052	(7,283)
Purchases of investment securities available for sale	(593,952)	(374,850)
Purchases of investment securities held to maturity	(116,028)	0
Purchases of marketable equity securities	(6,076)	(2,272)
Proceeds from maturities/calls of investment securities held to maturity	88,400	2
Proceeds from maturities/calls of investment securities available for sale	587,023	503,717
Proceeds from sales of marketable equity securities	119	664
Net decrease (increase) in overnight investments	(589,119)	(558,955)
Cash paid to the FDIC for shared-loss agreements	(8)	0
Proceeds from sales of other real estate	7,430	8,380
Proceeds from sales of premises and equipment	54	13
Purchases of premises and equipment	(23,875)	(24,081)
Net cash used in investing activities	(577,980)	(454,665)
FINANCING ACTIVITIES
Net decrease in time deposits	138,640	(92,064)
Net increase in demand and other interest-bearing deposits	387,319	795,034
Net decrease in short-term borrowings	(35,428)	(139,049)
Repayment of long-term obligations	(8,688)	(651,451)
Repurchase of common stock	(98,077)	0
Cash dividends paid	(4,668)	(4,204)
Net cash (used in) provided by financing activities	379,098	(91,734)
Change in cash and due from banks	(58,841)	(88,011)
Cash and due from banks at beginning of period	327,440	336,150
Cash and due from banks at end of period	268,599	248,139
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Transfers of loans to other real estate	2,613	6,582
Dividends declared but not paid	4,575	4,204
Transfer of Portfolio Loans (From) To Loans Held-for-sale	605	0
Transfers of premises and equipment to other real estate	520	0
Unsettled common stock repurchases	(2,679)	0
Initial recognition of operating lease assets	70,652	0
Initial recognition of operating lease liabilities	$ 71,793	$ 0