Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net earnings	$ 465,339	$ 357,818	$ 352,166
Depreciation and amortization	35,168	32,029	32,884
Accretion (Amortization) of Discounts and Premiums, Investments	23,938	41,450	39,797
Intangible asset amortization	22,506	14,240	16,517
Provision for credit losses	45,000	57,752	65,729
Gain on sale of foreclosed assets, net	(609)	(871)	(837)
Provision for losses on foreclosed assets	74	2,138	2,576
Gain on sale of loans and leases, net	(4,675)	(6,197)	(909)
(Gain) loss on sale of premises and equipment	(20)	(386)	78
(Gain) loss on sale of securities, net	(8,176)	541	(9,485)
Gain (Loss) on Sale of Insurance Block	(1,338)	(1,050)	(539)
Unrealized gain on derivatives and foreign currencies, net	(325)	(429)	(202)
Earned stock compensation	29,768	25,568	23,319
Gain (Loss) on Sale of Capital Leases, Net	0	0	720
(Increase) decrease in deferred income taxes, net	(136)	76,860	53,556
Tax effect included in stockholders' equity of restricted stock vesting	0	0	(4,406)
Decrease (increase) in other assets	25,117	(118,477)	6,441
(Decrease) increase in accrued interest payable and other liabilities	(23,604)	2,982	3,702
Net cash provided by operating activities	608,027	483,968	581,107
Cash flows from investing activities:
Cash acquired in acquisitions, net of cash consideration paid	0	160,318	0
Proceeds (Net Cash Used) From Branch Sale	0	0	(178,792)
Net increase in loans and leases	(1,209,986)	(1,303,752)	(1,257,734)
Proceeds from sales of loans and leases	646,587	1,322,456	121,053
Proceeds from maturities and paydowns of securities available-for-sale	290,177	435,925	250,170
Proceeds from sales of securities available-for-sale	571,800	759,300	393,509
Purchases of securities available-for-sale	(1,180,545)	(1,298,105)	(375,261)
Net (purchases) redemptions of Federal Home Loan Bank stock	(11,313)	12,982	(2,160)
Proceeds from sales of foreclosed assets	13,479	12,345	8,186
Purchases of premises and equipment, net	(12,385)	(7,919)	(8,183)
Proceeds from sales of premises and equipment	57	10,309	24
Proceeds from Sale and Collection of Lease Receivables	0	0	138,955
Proceeds from Life Insurance Policy	3,546	2,478	3,238
Net increase in equipment leased to others under operating leases	(28,610)	(73,596)	(51,557)
Net cash (used in) provided by investing activities	(917,193)	32,741	(958,552)
Cash flows from financing activities:
Net (decrease) increase in noninterest-bearing deposits	(615,263)	343,663	490,997
Net increase (decrease) in interest-bearing deposits	624,094	(63,700)	(104,021)
Net increase (decrease) in borrowings	903,772	(461,349)	285,928
Early Repayment of Subordinated Debt	(12,372)	0	0
Common stock repurchased and restricted stock surrendered	(315,542)	(109,153)	(33,244)
Tax effect of restricted stock vesting included in stockholders' equity	0	0	4,406
Cash dividends paid, net	(288,193)	(247,403)	(243,437)
Net cash provided by (used in) financing activities	296,496	(537,942)	400,629
Net (decrease) increase in cash and cash equivalents	(12,670)	(21,233)	23,184
Cash and cash equivalents, beginning of year	398,437	419,670	396,486
Cash and cash equivalents, end of year	385,767	398,437	419,670
Supplemental disclosures of cash flow information:
Cash paid for interest	119,042	69,477	54,389
Cash paid for income taxes	98,575	208,066	133,897
Real Estate Owned, Transfer to Real Estate Owned	16,914	580
Loans transferred to foreclosed assets		580	781
Transfer of Portfolio Loans and Leases to Held-for-sale	0	481,100	0
Common stock issued in acquisitions	$ 0	$ 446,233	$ 0